JPH0472851B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to an antiblocking agent made of anhydrous amorphous aluminosilicate, and its purpose is to provide excellent blocking ability for biaxially oriented films such as polyolefins and polyesters. The goal is to provide materials that demonstrate this. <Prior Art> Biaxially stretched films, such as polypropylene films, are widely used as various packaging materials. However, as is well known, this type of polyolefin film is sticky and prone to blocking, which not only impairs workability in film production and higher-order processing, but also impairs the use of the film. For example, when packaging or wrapping the bag, problems such as opening of the bag are likely to occur incorrectly. Therefore, this type of film is usually treated with anti-blocking treatment, and finely powdered silicic acid or kaolin clay is typically known and used as the anti-blocking agent. On the other hand, excellent transparency is required as a quality characteristic of polyolefin film, but this transparency and blocking resistance are contradictory. Although it is possible to increase the amount, the transparency decreases accordingly, so all conventional inorganic powders have drawbacks when used as modifying additives that can effectively satisfy both of these requirements. Ta. However, recently, it has been proposed to add zeolite powder to polypropylene in order to simultaneously satisfy both transparency and blocking resistance (Japanese Patent Publication No. 16134/1983). This zeolite powder is made by mechanically pulverizing natural products or granulated synthetic products into extremely fine powders, and it has relative transparency and durability compared to conventional clay or finely powdered silicic acid. Blocking properties have been improved. However, with natural products, the transparency and anti-blocking properties of the film vary widely and reproducibility is poor. Particularly in the case of mechanically pulverized particles, the major drawbacks are that the particle size distribution is necessarily wide, the particle surface is uneven, and there are complex fracture surfaces. Therefore, in order to improve this, the present inventors investigated and discovered that special particles of synthetic zeolite have excellent blocking resistance of polyolefin film, and have already filed a patent application (Patent Application No.
No. 300). <Problems to be Solved by the Invention> However, as is well known, zeolite contains water of crystallization, so under heating conditions during molding of synthetic resins and film formation, foaming phenomenon due to separation of water of crystallization often occurs, resulting in defects. I may give you a product. This defect is caused by the fact that even when zeolite is heat-treated to remove the so-called zeolite water and become anhydrous activated zeolite, this water is easily re-adsorbed. It was impossible to eliminate the effects. In view of the above facts, the present inventors,
As a result of extensive research to eliminate the effects of zeolite water while taking advantage of the excellent properties of zeolite, we have discovered that certain acid-treated zeolites retain the zeolite skeleton as is, and the heated products do not condense. The present invention was completed based on this fact and the discovery that it has an excellent anti-blocking effect on polyolefin films and polyester films due to its particle characteristics and refractive index characteristics. <Means for Solving the Problems> That is, the present invention is a synthetic zeolite treated with weak acidity and heating at least 200°C or above, which has a refractive index of 1.35 to 1.53 and whose primary particles are substantially spherical or spherical. It has a rounded particle shape and a smooth particle surface, and the average particle size is in the range of 0.5 to 5 μm, and the average particle size is 1/2 to 1 of the average particle size.
The present invention relates to an antiblocking agent characterized in that it consists of an anhydrous aluminosilicate substantially in the form of zeolite particles with a particle size fraction in the range of 1/2 of at least 50%. Generally, zeolite has the general formula (1.0±0.2)
M ₂ O・Al ₂ O ₃・xSiO ₂・yH ₂ O (where M is Na or an equivalent monovalent or polyvalent metal, x is often a value of 1.5 to 20, and y is a value of 0 to 10). It is an aluminosilicate with a unique crystal structure that can be identified by chemical composition and X-ray diffraction, and is known in a variety of forms, including natural minerals and synthetic products (usually M is Na ). Zeolites are also generally known to have unique adsorption and ion exchange properties based on their unique crystal structures, and a variety of uses have been developed that take advantage of these properties. Therefore, the antiblocking agent according to the present invention is a zeolite that has been acid-treated and heat-treated to substantially have a skeleton in the basic particle form, and preferably has a constant particle size distribution and refractive index. It is an anhydrous amorphous aluminosilicate with From this point of view, zeolites suitable as raw materials for producing the antiblocking agent of the present invention are those whose zeolite structure decomposes during acid treatment, and in many cases SiO ₂ /Al ₂ O ₃ (mol) It is a synthetic zeolite with a ratio of about 5 or less. Such zeolites include, for example, A-type zeolite, P-type zeolite, A type zeolite is preferred from the viewpoint of industrial significance. The above-mentioned synthetic zeolite is an equiaxed crystal, and in particular, as seen in type A zeolite, the primary particles are in a clear cubic crystal form, such as sugar cubes, but
The raw zeolite according to the present invention is produced by a special synthesis method so that its primary particles have a cubic rounded shape or a substantially spherical shape. Therefore, the antiblocking agent according to the present invention is an anhydrous amorphous aluminosilicate obtained by subjecting the above-mentioned zeolite to mildly acidic and heating treatment operations, but the basic characteristics such as the particle shape and particle size distribution of the zeolite are Weakly acidic treatment is particularly important in order to maintain the particle morphology as is. That is, in the present invention, weakly acidic treatment is performed by adding an acid or an acidic substance to an aqueous slurry of bulk zeolite so that the pH of the slurry is as low as 4.0, preferably 5.
The method is to adjust the acidity to a weak acidity of ~7 to destroy the crystal structure of the zeolite and make it amorphous. If the pH value is less than 4.5, it is unsuitable because the particle state of the zeolite changes significantly or the entire particle dissolves or disappears, destroying the skeleton of the bulk zeolite.On the other hand, if the pH value is higher than 9, it is unsuitable. The degree of crystallization becomes insufficient. Since the acid-treated raw zeolite contains the zeolite skeleton as it is, its anti-blocking ability strongly depends on the particle state of the zeolite. In particular, the antiblocking agent according to the present invention has particle characteristics such that the particle shape of the primary particles is substantially spherical or rounded with no corners, and the particle surface is smooth. It has characteristics. Such particle characteristics of the antiblocking agent are substantially the same as those of the bulk zeolite, and can be easily confirmed with an electron microscope as shown in the drawings. Furthermore, regarding the particle size, the average particle diameter is
It has a particle size distribution in the range of 0.5 to 5 μm, and the particle size portion in the range of 1/2 to 1 1/2 of the average particle size accounts for 50% or more of the total particle size. The above-mentioned amorphous aluminosilicate is clearly distinguished from zeolite in its physical properties by X-ray diffraction, and for example, the cation exchange ability characteristic of zeolite has substantially disappeared. Furthermore, although a normal dried product retains water, when heated and dehydrated, the powder becomes substantially anhydrous, although some equilibrium water content in the powder may be tolerated, and unlike zeolite, water does not condense. Therefore, in the antiblocking agent according to the present invention, the heat-treated product is
The above aluminosilicate is heated at a temperature of at least 200°C or higher, preferably 250 to 700°C to substantially dehydrate it. The heating and calcination temperature is also related to the calcination time, but high temperatures that would cause calcination between particles and impair dispersibility should be avoided, and the above range is practical. In the present invention, anhydrous refers to anhydrous in the form of Ig/Loss, which is obtained by dehydrating an amount of water equivalent to zeolite water through the heat treatment described above, but in general, anhydrous inorganic powder is also anhydrous in the form of Ig/Loss. Depending on the moisture,
The equilibrium water concentration that is inevitably adsorbed can be tolerated. In addition, in the present invention, amorphous means
This includes those in which no diffraction lines are observed in the line diffraction diagram, and those in which the height of the diffraction lines is reduced to less than half that of zeolite, making it substantially amorphous. On the other hand, in addition to its performance, antiblocking agents are required to have a property that does not impair the transparency of the film when added to the film, and in general, transparency and blocking resistance are contradictory properties. However, since the antiblocking agent according to the present invention has a refractive index adjusted to 1.35 to 1.53, it is close to the refractive index of polyolefin or polyester films, so it can substantially improve transparency. There is no harm to it. This refractive index varies depending on the type of bulk zeolite, its physical properties, acid, and heat treatment conditions, and is also affected by cation substitution, so it is within the range of the bulk zeolite or amorphous zeolite. Preferably, a high quality aluminosilicate is prepared. Therefore, anhydrous amorphous aluminosilicate is
Although it itself has excellent performance as an antiblocking agent, it may be modified to some extent as necessary to suit the purpose of use. Due to the small amount of cation exchange ability remaining as such a modified product, other cations such as Ca,
Mg, Ba, Zn, Pb, etc. may be slightly substituted with Na ⁺ , or coating treatment with amorphous silica or metal hydroxide may be applied. For example, typical coating treatments include coatings with a continuous film of dense and fine amorphous silica, or fine white metal hydrated oxides such as aluminum, titanium, zirconium, antimony, etc. or modification of the particle surface with surfactants, dispersants, etc. The antiblocking agent according to the present invention is an anhydrous amorphous aluminosilicate as described above, and preferably has the above particle characteristics and refractive index, but on the other hand, it is particularly suitable for the resin film applied thereto. Although there is no limitation, it is particularly suitable for films such as polyolefin and polyester. The polyolefin is not particularly limited as long as it has the ability to form a transparent and crystalline self-supporting film.
A crystalline homopolymer of about 12 α-olefins or a crystalline copolymer of two or more types, specifically polyethylene, polypropylene, poly-4-methylpentene-1, ethylene-propylene random or block copolymer, Examples include ethylene-propylene-butene copolymer and ethylene-propylene-hexene copolymer. Among these, polypropylene, a copolymer of propylene with a majority weight of propylene and another α-olefin, or a copolymer of ethylene and another α-olefin is preferable, and in particular, a propylene polymer with an ethylene content of 0 to 6% by weight is good. Further, these polyolefins are crystalline, and those having an isotactic index (II) of usually 40 or more, particularly 60 or more, particularly 90 or more are suitable. Furthermore, it is used as long as it can be molded, but usually the melt flow rate (MFR) is
0.01 to 100 g/10 minutes, especially 0.1 to 50 g/10 minutes, especially 0.5 to 10 g/10 minutes are preferred. In addition, as polyester, terephthalic acid or terephthalic acid dialkyl ester and general formula HO
(CH ₂ ) _o OH [in the formula, n represents an integer of 1 to 10], which is a reaction product with alkylene glycol such as ethylene glycol, trimethylene glycol, hexamethylene glycol, and cyclohexanedimethanol. Other functional compounds which react with terephthalic acid or terephthalic acid dialkyl esters to give linear polyesters may also be P-xylene glycol, hydroquinone and cyclic glycols. It may also be a polyester containing modifiers such as dibasic acids including isophthalic acid, sebacic acid, adipic acid, sulfonated derivatives, and the like. Other polymer films that can be used include polyamides such as nylon 66 and nylon 6, and halogen-containing polymers such as polyvinyl chloride. The amount that should be added to such a polymer as an antiblocking agent depends on the type of polymer, the purpose of the film,
Although it varies depending on the physical properties of the antiblocking agent, in most cases it is 0.01 parts by weight per 100 parts by weight of the polymer.
-1 part by weight is suitable, particularly preferably 0.03-0.5 part by weight. The reason for this is that if the amount is less than 0.01 part by weight, the desired effect will not be sufficiently expressed and the accuracy of blending into the polymer and uniformly dispersing it will decrease; If it exceeds this amount, the transparency of the film will be impaired, the blocking resistance will not be improved in proportion to the amount added, and the stretchability of the film will also be reduced. It is of course possible to use other additives used in polymers, such as various antioxidants, stabilizers, processing aids, colorants, antistatic agents, but rather Antiblocking agents often act to enhance and bring out the performance of these additives, and more favorable effects may be observed. <Effects of the Invention> When producing a film using the antiblocking agent according to the present invention, for example, a polyolefin composition can be biaxially stretched in a conventional manner to achieve good workability, non-foaming transparency, and durability. A film with good blocking properties can be produced. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. The evaluation was conducted using the following test method. Particle size distribution: Measured using a Coaster counter (manufactured by Coulter Electronics) with an aperture tube diameter of 20 μm. [Ca ion exchange capacity] Calcium chloride solution (300mg/as CaO)
Add 1 g of sample (calculated as anhydride) to 1, react by stirring at 25°C, and after 15 minutes, immediately filter and separate the zeolite, analyze the concentration of calcium (CaO) in the solution, and determine the amount of calcium (CaO) dissolved by the reaction. Calculate the amount of decrease in calcium and use this as the Ca ion exchange capacity. [Composition analysis] By atomic absorption spectrophotometry. [Measurement of moisture] Approximately 1 g of the sample was weighed into a porcelain crucible and heated to 800°C.
It was determined from the weight loss after heating for a certain period of time. [Refractive index] Measured by Larsen's oil immersion method using Atsube's refractometer. [Measurement of equilibrium PH] 5 g of sample powder was dispersed in 100 ml of ion-exchanged water with a pH of 7.0, and after stirring at 25° C. for 30 minutes, the PH was measured with a PH meter (M-5, manufactured by Hitachi Horiba). Example 1 Na-A type zeolite which is a substantially spherical primary particle synthesized by instantaneous reaction in a 500 c.c. beaker
Weigh 50g and add 200g of water to determine the zeolite concentration.
250g of 20% slurry was prepared. Note that the pH of this slurry was 11.7. While stirring the slurry, 250 g of 4% sulfuric acid was gradually added thereto over about 5 minutes. After the addition, stirring was continued for 1 hour (during which time the pH of the slurry was always maintained at 4 or higher), and then Filtration, water washing, drying and pulverization were performed to obtain an acid-treated Na-A zeolite product. When this acid-treated product was subjected to X-ray diffraction (XRD) analysis, no diffraction peaks were observed, indicating that it was an amorphous aluminosilicate. Next, this acid-treated product was heat-treated at a temperature of about 300°C for 2 hours to dehydrate it, and if necessary, it was lightly crushed to obtain an antiblocking agent as shown in the electron micrograph of Figure 1. . FIG. 2 shows an electron micrograph of the bulk zeolite, and Table 1 shows the physical properties of the bulk zeolite as well as the above-mentioned antiblocking agent. As is clear from these drawings and Table 1, the antiblocking agent according to the present invention retains the particle state of the original zeolite, that is, the skeleton. Example 2 An antiblocking agent was obtained in exactly the same manner as in Example 1 except that the same Na-A zeolite as in Example 1 was used and 2% sulfuric acid was used instead of 4% sulfuric acid. In XRD analysis, the intensity of each diffraction peak of Na-A type zeolite was reduced to about 11/3 to 1/4, and it is clear that this product contains a large amount of amorphous aluminosilicate. The particle size distribution, average particle diameter, Ca ion exchange capacity, composition, etc. of this antiblocking agent are also shown in Table 1. Example 3 Using the same Na-A zeolite as in Example 1,
An antiblocking agent was obtained in exactly the same manner as in Example 1 except that 10% phosphoric acid was used instead of 4% sulfuric acid. No diffraction peak was observed in this product by XRD analysis, and it is clear that it is an amorphous aluminosilicate. Particle size distribution, average particle size, Ca ion exchange capacity,
The composition etc. are also shown in Table 1. Example 4 Using the same Na-A zeolite as in Example 1, an antiblocking agent was obtained in exactly the same manner as in Example 1, except that 4% sulfuric acid was slowly added over about 30 minutes. This material was found to be Na− in XRD analysis.
No diffraction peak of type A zeolite was observed,
It is clear that it is an amorphous aluminosilicate. The particle size distribution, average particle diameter, Ca ion exchange capacity, composition, etc. of this antiblocking agent are also shown in Table 1. Example 5 Na-X zeolite, which is a substantially spherical primary particle synthesized by instantaneous reaction (average particle size 2.5μ,
A slurry was prepared in the same manner as in Example 1.The slurry was prepared in the same manner as in Example 1. Next, 5% phosphoric acid was gradually added, and the addition was terminated at pH 4.7. Next, filtration, washing with water, drying and pulverization were performed in a conventional manner to obtain an acid-treated product of Na-X zeolite. When this acid-treated product was observed under an electron microscope, it was found that the particle state was exactly the same as the original zeolite, and even when the particle size was measured, it was almost the same as the original zeolite particles, and there was no difference in appearance from the original zeolite particles. However, X-ray diffraction (XRD) analysis showed that it was amorphous. then 350
An antiblocking agent was obtained by heat treatment at ℃ for 2 hours.

[Table] The various antiblocking agents listed above, raw zeolite as a comparative example, hydrous amorphous aluminosilicate that was not heat-treated in Example 1, and commercially available synthetic silica (average particle size) used as an antiblocking agent. A polypropylene composition was prepared in the following manner using a polypropylene film (diameter: 0.8μ) to obtain a biaxially stretched polypropylene film, and its quality was evaluated. The results were as shown in Table 2. Production of film 100 parts by weight of polypropylene resin with a melt flow rate of 1.9 g/10 minutes was added with 2.
0.10 parts by weight of 6-di-t-butyl-p-cresol, 0.02 parts by weight of Irganox 1010, 0.05 parts by weight of calcium stearate as a hydrochloric acid catch agent, and the antiblocking agent according to the present invention.
They were added in varying amounts of 0.01 part by weight, 0.04 part by weight, and 0.08 part by weight, mixed in a super mixer, and then pelletized in an extruder. Separately, as an inorganic additive, type A zeolite as a raw material,
A blank containing no synthetic silica or other inorganic additives was prepared in the same manner. The pellets were made into a sheet-like film using an extruder, and stretched 5 times in the longitudinal direction and 10 times in the transverse direction to finally obtain a stretched film with a thickness of 30 μm. One side of the stretched film was subjected to corona discharge treatment. For these biaxially oriented films, transparency,
Blocking property and heat resistance were measured. The transparency of the film was measured by stacking four films in accordance with ASTM-D-1003. The blocking property of the film is determined by stacking the two films so that the contact area is 10 cm ² and placing them between two glass plates at 40°C under a load of 50 g/cm ² .
After leaving it in the atmosphere for 7 days, it was peeled off using a Schottsper type tester at a tensile speed of 500 mm/min.
The maximum load was read and evaluated. The foamability of the film was determined by kneading a mixture of 100 parts of resin (polyethylene (SMA-110)) and 1 part of the sample with a roll at 170°C for 5 minutes, and then press-molding it to a thickness of 1 mm at 170°C for 4 minutes. to obtain a sample plate.
The sample plate was sandwiched between glass plates like sandwich layers and left in a heating oven at 230°C for 1 hour to observe the foaming state.

[Table] Foaming properties were evaluated from 1 to 1 for those that did not foam at all, similar to the blank.
The results were expressed in 4 stages, with 4 being the most foamed product.

[Brief explanation of the drawing]

Figure 1 is an electron micrograph showing the particle structure of the antiblocking agent of the present invention, and Figure 2 is the Na
- An electron micrograph of type A zeolite is shown.

Claims (1)

[Claims] 1 Weak acidity of synthetic zeolite and at least
A product processed by heating at 200°C or higher, with a refractive index of 1.35 to 1.53, primary particles having a substantially spherical or rounded particle shape and a smooth particle surface,
And the particle state of the zeolite has an average particle size in the range of 0.5 to 5 μm, and the particle size portion in the range of 1/2 to 1 1/2 of the average particle size is at least 50%. An antiblocking agent characterized by comprising anhydrous aluminosilicate.