JPH0144248B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to moldable granular polyolefin materials coated with additives such as fillers, stabilizers, pigments and the like. Specifically, the present invention relates to a granular polyolefin material for molding, in which a compounding agent is adhered to the surface of a granular crystalline polyolefin in a layered manner using a binder. Conventionally, it has been common practice to add compounding agents such as fillers, stabilizers, and pigments to polyolefin, heat, melt, knead, and granulate the composition to produce pellets, which are then molded. However, pelletizing requires a large amount of energy and requires expensive equipment, which is industrially disadvantageous. Therefore, attempts have also been made to directly mix granular polyolefin and compounding agents and subject the mixture to molding without going through the granulation process. however,
Simply mixing compounding agents such as stabilizers, pigments, fillers, etc. with granular polyolefin has the disadvantage that the compounding agents are not uniformly dispersed in the polyolefin, which in turn has an adverse effect on the resulting molded product. In particular, among compounding agents, fillers are generally added in larger amounts than stabilizers, pigments, etc., and are finer than granular polyolefins and have a lower bulk specific gravity. Furthermore, when such a mixture is used in a molding process, such as an injection molding process, the following problems arise. Fine powder filler is scattered during operations such as charging into a hopper and transferring from one hopper to another. The molding material is poorly bited into the screw, and the time for plasticization becomes longer, reducing moldability. In addition, there is a large amount of trapped air, which results in insufficient deaeration, resulting in silver streaks, burns, etc. on the molded product. Due to uneven dispersion of the filler within the molded product, the appearance and mechanical properties of the molded product are poor. These drawbacks become more pronounced as the amount of filler added increases. For the above-mentioned reasons, it is generally not possible to directly mold a mixture, but at present the mixture is once formed into pellets and then used for molding. The present inventors have conducted intensive studies to obtain a polyolefin molding material that is composed of granular polyolefin and a compounding agent and can be directly molded by omitting the pelletizing step, and as a result, the compounding agent was attached to the surface of the granular polyolefin using a binder. The present invention was achieved by discovering that a granular polyolefin material for molding has excellent moldability and can give uniform molded products. That is, the present invention is a molding method characterized by having at least one layer consisting of at least one compounding agent and a binder on the surface of a granular polyolefin having a bulk specific gravity of 0.45 or more and a particle size distribution of 150 to 2000 microns. Provides a granular polyolefin material for use. The granular polyolefin material for molding of the present invention has individual polyolefin particles as the core, and the compounding agent is firmly attached to the surface by a binder, so it has a high bulk specific gravity, good fluidity, and can be directly subjected to molding processing. The molded products obtained using this method have good dispersion of the compounding agents, and therefore are equivalent in appearance, mechanical properties, etc. to molded products obtained by molding conventional pellets. The present invention will be explained in detail below. The granular polyolefins used in the present invention include homopolymers of ethylene and propylene, random copolymers and block copolymers of ethylene and other α-olefins, or propylene and other α-olefins, and are preferably These polyolefins are crystalline and have a bulk specific gravity of 0.45 or more and a particle size distribution of 150 to 2000 microns. If the bulk specific gravity is less than 0.45, it is not preferable because there are many voids inside the grains and between the grains, and sufficient deaeration cannot be achieved during molding. If the particle size is too small, it is not preferable because it tends to scatter, and especially if it is less than 100 microns, it is likely to cause a dust explosion.
On the other hand, if the particle size is too large, the dispersion of the compounding agent in the resulting molded article will be poor. Further, the shape of the granular polyolefin is preferably as close to a spherical shape as possible, and the narrower the particle size distribution. The properties of granular polyolefin are basically determined by the polymerization catalyst used during its production. As an example of producing a polyolefin with preferable properties suitable for the present invention, a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and further activating the polymer is shown. propylene or propylene and other olefins in an inert solvent or in the substantial absence of an inert solvent using a catalyst system consisting of an organoaluminium compound and, if necessary, an electron-donating compound. Obtained by polymerization in propylene or in the gas phase. A specific example of a method for producing a titanium trichloride composition is as follows:
JP-A-47-34478, JP-A-51-76196, JP-A-53-33289, JP-A-54-112973
Publication No. 119576, Japanese Patent Application Laid-open No. 119576, Japanese Patent Publication No. 1983-
Many proposals have been made, including Publication No. 11985. In addition, the compounding agent referred to in the present invention refers to fillers conventionally added to improve the physical properties of polyolefin,
Stabilizers, pigments and other various auxiliaries are meant. The amount of these deposited is no different from the amount conventionally added to polyolefin. Fillers include silica, diatomaceous earth, alumina,
Titanium oxide, iron oxide, zinc oxide, magnesium oxide, pumice powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, talc, clay,
Examples include inorganic fillers such as mica, glass beads, and carbon black; organic fillers such as wood powder, paint residue, pulp, and paper powder; and mixtures thereof. There is no particular limit to the size of the filler, but it is usually 50
The filler is less than a micron, preferably less than 30 microns, and it is preferable to use a finer filler as the particle size of the core particulate polyolefin is smaller, so the filler may be appropriately selected in consideration of the average particle size of the particulate polyolefin. In addition, the amount of filler deposited on granular polyolefin
Usually 10 to 200 parts by weight per 100 parts by weight, preferably
It ranges from 10 to 150 parts by weight. Conventionally, stabilizers include various antioxidants, which are added to improve the stability and quality of polyolefins.
These are light stabilizers and the like, and one or more kinds of them are used. An example of a stabilizer is antioxidant 2,
6-Ditertsiabutylvalacresol, calcium stearate, tetra[methylene-3-(3,
5 ditertsiabutyl-4-hydroxyphenyl) propionate] methane, etc.; as a light stabilizer, 2-(2'-hydroxy-5'-methylphenyl);
Examples include, but are not limited to, benzotriazole and 2-hydroxy-4-octylbenzophenone. Other various auxiliary agents include antimony oxide, flame retardants such as dodecachloropentacyclodecane, and lubricants. Some of these stabilizers have a melting point lower than that of the granular polyolefin, and they have a similar effect to a binder, but if they are used alone, fillers, other stabilizers, pigments, etc. It cannot adhere uniformly and firmly, and the pigment is an organic or inorganic pigment used for coloring polyolefins. The binder is a filler on the surface of the granular polyolefin.
A layer of compounding agents such as stabilizers has the role of ensuring strong adhesion. The binder is preferably one that has good compatibility with the core particulate polyolefin. If the compatibility is poor and the amount of binder is large, it is not preferable because when the molding material is processed into a molding material, surface dispersion tends to be poor and the quality of the molded product tends to deteriorate. Examples of binders include polyethylene, ethylene-
Vinyl acetate copolymers, ethylene-unsaturated carboxylic acid ester copolymers (e.g. ethylene-methyl methacrylate copolymers, etc.), ethylene, unsaturated carboxylic acid metal salt copolymers (e.g. ethylene-magnesium acrylate or zinc copolymers) polymers, etc.), copolymers of propylene and other olefins (propylene-ethylene copolymers, propylene-butene copolymers,
1 copolymer, etc.), polyethylene or polypropylene modified with an unsaturated carboxylic acid such as maleic anhydride, ethylene-propylene rubber, olefin copolymers such as atactic polypropylene, petroleum resins, and the like. Olefin polymers are particularly preferred. For example, molded articles of polyolefin to which fillers are added generally have higher rigidity but lower impact strength than molded articles without additives. On the other hand, it is preferable to use an olefin polymer as the binder in the granular polyolefin material for molding of the present invention because the impact resistance strength is less reduced or the strength is improved. For example, when granular polypropylene is used, it is preferable to use polyethylene, propylene-butene-1 copolymer, ethylene-propylene rubber, or adhesive polypropylene as the binder because the impact strength will be improved. These binders may be used alone or in combination. The binder preferably has a melting point that is at least 3° C. lower than the melting point of the core particulate polyolefin, from the standpoint of manufacturing and material molding, and may be appropriately selected in consideration of the melting point of the particulate polyolefin. The amount of binder varies depending on the type and amount of the compounding agent, so it can be determined appropriately taking these into consideration, but if the amount of filler attached is 10 to 200 parts by weight per 100 parts by weight of granular polyolefin, it is usually difficult to bind. The agent/filler weight ratio is about 1/10 to about 1/2, preferably about 1/2.
10 to about 1/5. In the case of other compounding agents, they may be appropriately determined in consideration of the amount of adhesion, but since the amount added is generally smaller than that of fillers, the amount of the binder may be greater than the amount of the compounding agents. An example of the method for producing the granular polyolefin material for molding of the present invention will be described below. The equipment used is a mixer with an agitator equipped with a jacket for high-speed fluidization, and a mixer that can heat the contents, such as a high-speed mixer for dry blending of granular resin, such as a Henschel mixer, Examples include Super Mixer (trade name, manufactured by Kawada Seisakusho Co., Ltd.). Inside this mixer, granular polyolefin,
While mixing the binder and at least one compounding agent, the mixture is heated to a temperature slightly higher than the melting point of the binder. As a result, the dissolved binder, including the compounding agent, firmly and uniformly adheres to the surface of the granular polyolefin. If this is taken out as it is or after being slightly cooled, a granular polyolefin for molding with good fluidity can be obtained. When produced by this method, it is preferred to use a binder whose melting point is at least 3° C. lower than the melting point of the particulate polyolefin. This is to prevent the granular polyolefin from melting, and considering only this point, the larger the difference in melting point, the better. Further, in order to improve the dispersion of the binder and melt the binder in a short time, it is suitable that the binder has an average particle size of 1000 microns or less and is smaller than the particle size of the granular polyolefin used. Next, by appropriately changing the mixing order of the granular polyolefin, the binder, and at least one compounding agent, the heating timing, etc., the composition and structure of the layer formed on the surface of the granular polyolefin can be changed. Some examples are shown below, but the present invention is not limited thereto. granular polyolefin, binder, at least one
When the seeds are placed in a mixer all at once and heated while being mixed, a uniform single layer of the binder and the compounding agent is formed on the surface of the granular polyolefin. This method is sufficient when the amount of compounding agents such as stabilizers and pigments used is small, or when the amount of fillers is small. This method is suitable when the compounding agent is a filler and its amount is large. That is, part of the granular polyolefin and filler, and possibly other ingredients such as stabilizers, are placed in a mixer,
3 below the melting point of the granular polyolefin while mixing.
Heat the granular polyolefin to a temperature about 20°C lower to form a layer mainly composed of the filler on the surface of the polyolefin granules, then add the remaining filler and binder to the mixer (in any order, mix both in advance) ), and while mixing, heat and raise the temperature to a temperature lower than the melting point of the granular polyolefin but higher than the melting point of the binder. As a result, a molding material is obtained which has a dense layer of, for example, stabilizers and pigments on the inside and a layer mainly composed of fillers and binders on the outside. Although the molded product obtained using this method has a large amount of filler, the filler is well dispersed. This method also allows the amount of binder used to be reduced. First, granular polyolefin and ingredients other than fillers (for example, stabilizers, pigments, etc.) are added and mixed. Next, the filler and binder are placed in a mixer and mixed while being heated to a temperature lower than the melting point of the granular polyolefin but higher than the melting point of the binder. As a result, a molding material is obtained which has a dense layer of, for example, stabilizers and pigments on the inside and a layer mainly composed of fillers and binders on the outside. Molded articles obtained using this method have particularly good dispersion of compounding agents such as pigments in the inner layer. Note that a granular polyolefin material for molding in which a layer containing a stabilizer, particularly a thick layer, is formed on the surface of the granular polyolefin has the advantage that deterioration of the polyolefin over time is suppressed and can be stored for a long time. The molding material of the present invention can be subjected to generally known molding processes such as injection molding, blow molding, extrusion molding, and sheet molding without undergoing a pelletizing process.
Filled polyolefin molded products obtained by these molding methods, for example, have good filler dispersion and are used in automobile parts (car heaters, car cooler cases, instrument panels), household electrical appliances, and futon dryers. It is suitable for use as outer frames and stands of vacuum cleaners, speakers, record players, etc., and other parts. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Example 1 (1) Polymerization of propylene A stirred stainless steel autoclave with an internal volume of 3000 was purged with nitrogen, and 1800 g of diethylaluminum chloride was prepared as shown in Example 15 and Catalyst Preparation Method 3 of JP-A-53-33289. 50g of titanium trichloride solid catalyst (B) obtained by the method
was charged, and hydrogen corresponding to a partial pressure of 0.5 Kg/cm ² was added. Then, 840 kg of liquid propylene was pressurized into the autoclave, and the autoclave was kept at 65°C to continue polymerization for 4 hours. After the polymerization was completed, unreacted monomers were purged and methanol 60% was added to decompose the catalyst. Separate the produced polypropylene using a centrifuge and store it at 60°C.
When dried under reduced pressure, spherical polypropylene of uniform particle size of 390 kg was obtained. The melting point of this polypropylene was measured with a differential thermal calorimeter (manufactured by PerkinElmer) and was found to be 165°C. The particle size distribution of this granular polypropylene is 200~
The average particle size was about 600 microns, and the bulk specific gravity was about 0.49. (2) Production of molding material Steam of 1 kg/cm ² G was passed through a 300 Super Mixer (trade name, manufactured by Kawada Seisakusho Co., Ltd.).
To this, (1) 22.5 kg of granular polypropylene obtained by polymerization of propylene and a stabilizer {tertiarybutyl p-cresol:tetra[methylene-3-(3,
5-ditertyabutyl-4-hydroxyphenyl)propionate methane = 2:1 (weight ratio)} 120g, Sumikacene G801 as a binder
720r
Stirred at pm. When the temperature reached 115°C 12 minutes after the start of stirring, the contents were extracted, and a spherical, smooth polypropylene material with a large bulk specific gravity for molding was obtained. The talc adhered uniformly and firmly to the granular polypropylene, and no peeling of the talc was observed even when it was placed in the palm of the hand and rubbed strongly with the fingertips. Almost no adhesion was observed on the inner wall of the super mixer. (3) Molding This granular polypropylene material for molding was molded using an injection molding machine (M-32-SJ manufactured by Meiki Seisakusho Co., Ltd., screw diameter 25 mm, injection amount 1 ounce). Good biting into the screw and plasticizing time is 12~
It was hot in 13 seconds. The obtained molded product had a good appearance without silver streaks or bubbles.
A part of the molded product was hot-pressed into a thin sheet and the state of dispersion of talc was observed, and it was found that the dispersion was good. Example 2 (1) Formulation 15 kg of granular polypropylene obtained in Example 1-(1)
90 kg of the same stabilizer used in Example 1, 3 kg of Sumikasen G801, and 12 kg of calcium carbonate powder with an average particle size of 10 microns were mixed in the same manner as in Example 1-(2). A molding material with good properties was obtained and free calcium carbonate was not present. The properties of this molding material are shown in Table 1. (2) Molding This molding material was molded under the same conditions as in Example 1-(3). The results are shown in Table 2. Example 3 (1) Manufacturing method of molding material Granular polypropylene obtained in Example 1-(1)
Stabilizer similar to that used in Example 1 for 23.4Kg
Add 120g and 3.0Kg of talc, mix and heat to 145℃
The temperature rose to At this point, most of the talc was attached to the surface of the granular polypropylene. Next, the remaining talc 3.0Kg, then Sumikasen G801
0.6 kg of powder was added and mixed for an additional 5 minutes.
Thereafter, the steam supply to the jacket of the super mixer was stopped, and the supply of cooling water was switched to cooled to 80°C, after which the contents were extracted. A free-flowing molding material free of spherical free talc was obtained. The results are shown in Table 1. (2) Molding This molding material was molded in the same manner as in Example 1-(3). The results are shown in Table-2. Example 4 (1) Production of molding material Granular polypropylene obtained in Example 1-(1)
22.5Kg and a stabilizer similar to that used in Example 1
120g, 1.5kg of high-density polyethylene powder (melting point 140°C) as a binder, and 6kg of talc with an average particle size of 8 microns were charged into a super mixer.
Pass 2Kg/cm ² G of steam through the jacket.
Stirred at 720 rpm. 22 minutes after starting stirring, the temperature reached 145℃, so I stopped the steam and switched to cooling water.
Stirred at 360 rpm. It was taken out when the temperature reached 80°C. A spherical and smooth molding material having properties similar to those of Example 1-(2) was obtained. (2) Molding This molding material was molded under the same conditions as in Example 1-(3). The results are shown in Table-2. Example 5 (1) Production of molding material Propylene-butene-1 copolymer (butene-1 content 18% by weight, melting point 140°C) as a binder
The same procedure as in Example 4-(1) was carried out except that .
A free talc-free molding material similar to Example 4-(1) was obtained. The results are shown in Table-1. (2) Molding This molding material was molded under the same conditions as in Example 1-(3). The results are shown in Table-2. Example 6 (1) Production of molding material Granular polypropylene obtained in Example 1 22.5
Kg and 120 g of stabilizer similar to that used in Example 1
was added to the super mixer. Jacket 1
Kg/cm ² G steam was passed through and stirred at 720 rpm.
When the temperature reached 115°C, the rotation was reduced to 360 rpm, and 1.5 kg of Sumikasen G801 powder and talc 6, which had been mixed in advance, were mixed together.
Kg was added, mixed for 5 minutes and discharged. All of the talc adhered to the surface of the granular polypropylene, resulting in a spherical, smooth molding material. The results are shown in Table-1. After the mixing was completed, the inside of the super mixer was inspected, and there was almost no polymer adhesion to the inner wall. (2) Molding This molding material was molded under the same conditions as in Example 1-(3). The results are shown in Table-2. Comparative Examples 1 and 2 (1) Production of molding material The same procedure as in Example 1-(2) and Example 2-(1) was carried out except that the mixing conditions in the super mixer were 35°C and 3 minutes. Most of the talc and calcium carbonate were liberated from the powdered polypropylene, and a layer consisting of the binder and compounding agent was not substantially formed, resulting in only a mixture with poor fluidity. (2) Molding Each of these molding materials was molded under the same conditions as in Example 1-(3). The results are shown in Table 2. Comparative Example 3 (1) Production of molding material The same procedure as in Example 1-(2) was carried out except that no binder was used. Only a molding material containing a large amount of free talc was obtained, and some of the talc was attached to the granular polypropylene, but the talc could be peeled off by simply rubbing it lightly with a finger. (2) Molding This molding material was molded under the same conditions as in Example 1-(3). The results are shown in Table 2. Comparative Example 4 (1) Production of molding material Same as Example 1 except that 1.5 kg of zinc stearate (melting point 120°C), which is a type of stabilizer, was used instead of the binder and the temperature during mixing was 125°C. Most of the talc was attached to the granular polypropylene, but it was easily removed by rubbing it with your fingers. Reference Example (1) Granular polypropylene, the stabilizer Sumikasen G801, and talc in the amounts shown in Example 1-(2) were simply mixed, and this mixture was melt-kneaded in a screw-type extruder at a temperature of 230°C to form pellets. It became. (2) Molding This pellet was molded in the same manner as in Example 1-(3). The results are shown in Table-2. Table 2 shows that the molding material of the present invention has moldability equivalent to that obtained by molding conventional pellets.
It is clear that it gives a molded article.

【table】

[Table] Example 7 Comparative Example 5 Next, in order to demonstrate that the economical deterioration of the molding materials is suppressed, a portion of the molding materials of Example 1 and Comparative Example 1 were each used in a screw type extruder after a certain period of time had elapsed. The mixture was melted and kneaded at 230°C using a pelletizer to form pellets, and the melt index (according to ASTM D1238-65T) was measured. Table 3 shows the results. The higher the melt index, the more advanced the deterioration is.

[Table] This result shows that the molding material of the present invention does not deteriorate over time and can be stored for a long time.

Claims (1)

[Claims] 1. A compounding agent containing 10 to 200 parts by weight of a filler per 100 parts by weight of the granular polyolefin on the surface of a granular crystalline polyolefin with a bulk specific gravity of 0.45 or more and a particle size distribution of 150 to 2000 microns. and a binder which is an olefinic polymer having a melting point at least 3° C. lower than the melting point of the granular polyolefin. 2. The granular polyolefin material for molding according to claim 1, wherein the granular crystalline polyolefin is propylene alone or a copolymer. 3. The granular polyolefin material for molding according to claim 1, which has one layer. 4. The granular polyolefin material for molding according to claim 1, wherein the layer comprises an inner dense layer of filler and an outer layer of binder-based filler. 5. The layers consist of an inner stabilizer or a dense layer of stabilizer and pigment, optionally further auxiliary agents, and an outer filler and binder-based layer. The granular polyolefin material for molding described.