JPS6367494B2 - - Google Patents

Description

[Detailed description of the invention]

[] Object of the Invention The present invention relates to a crystalline olefin resin composition. More specifically, it relates to a crystalline olefin resin composition comprising (A) a crystalline olefin resin, (B) an oxyacid, and (C) an inorganic carbonate;
The purpose is to provide a crystalline olefin resin molded product with excellent dimensional stability. [] Background of the Invention Crystalline olefin resins, such as high-density polyethylene, medium-density polyethylene, chain low-density polyethylene, and high-pressure processed low-density polyethylene, have high crystallinity and have poor mechanical, chemical, and thermal properties. , it has excellent properties such as electrical properties and workability, so it is used in a wide variety of fields. However, in the process of obtaining a molded article from a molten state, it undergoes crystallization and solidification, resulting in a much larger change in density than in an amorphous olefin resin. As a result, especially in injection molding, the finished dimensions of the mold become smaller,
Thick molded products have drawbacks such as sink marks and warpage due to anisotropy of shrinkage rate. Conventionally, methods to improve these drawbacks include methods for obtaining molded products using special molds, methods for highly filling inorganic materials, methods for adding nucleating agents, methods for molding under special molding conditions, and methods for molding using ordinary chemistry. Methods such as adding a foaming agent are used. However, with the method using a special mold,
The design of the molded product is limited, the method of high filling with inorganic substances causes deterioration of physical properties and the surface gloss of moldability, and the method of adding a nucleating agent does not have sufficient improvement effect, and special If the molding process is carried out under different molding conditions, the molding cycle becomes longer, and if a conventional chemical blowing agent is added, foaming may occur on the surface of the molded product, and the surface of the molded product may become rough. It had problems such as (disadvantages). Based on the above, the present inventors have conducted various searches to obtain molded products of crystalline olefin resin that do not have these drawbacks and have particularly excellent dimensional stability.As a result, (A) Crystalline olefin resin (B) 100 parts by weight of strong crystalline olefin resin, 0.01
Oxy acid-containing crystalline olefin resin mixture obtained by mixing ~30 parts by weight of oxy acid and (C) 0.01 to 100 parts by weight of crystalline olefin resin
It is a composition consisting of an inorganic carbonate-containing crystalline olefin resin mixture obtained by mixing 30 parts by weight of an inorganic carbonate, and the oxy-acid-containing crystalline olefin resin mixture and inorganic Among carbonate-containing crystalline olefin resin mixtures, crystalline olefin resin compositions in which the blending ratio of any one of them is 0.5 to 99% by weight do not have the above-mentioned problems and have excellent dimensional stability. We have previously proposed a composition that allows the production of molded articles. [] Structure of the Invention Similarly to the above, the present inventors have further explored the possibility of obtaining a molded product of crystalline olefin resin that does not have the above-mentioned drawbacks and has particularly excellent dimensional stability. It is a composition consisting of A) crystalline olefin resin (B) oxyacid and (C) inorganic carbonate, and the proportion of oxyacid and inorganic carbonate in the total composition is calculated as the total amount.
0.01 to 40% by weight, and the ratio of the inorganic carbonate to the oxyacid is 1:0.1 to 1:10 as an equivalent equivalent, The inventors have discovered that the composition does not have the following problems (defects) and can produce molded articles with excellent dimensional stability, and have arrived at the present invention. [] Effects of the Invention The molded product of the composition obtained by the present invention not only has excellent dimensional stability, but also has the following characteristics (effects). (1) The surface is in good condition, so the appearance is beautiful. (2) Since the composition has excellent moldability, molded products of various shapes can be obtained. (3) Since the composition has excellent moldability (processability), molded products can be obtained even with a short molding cycle. (4) There is almost no deterioration in physical properties. (5) Almost no whiskers or warpage can be seen on the molded product. (6) Since the inside of the molded product is foamed, it is lightweight. The above shows that when the resin pellet mixture (composition) of the present invention is heat-molded at the molding temperature generally used for olefin resins (120 to 350°C), only the inside of the resulting molded product foams uniformly. Therefore, the shrinkage rate is small, there is no so-called warpage or sink marks, and the surface condition of the molded product is good. When producing foams using commonly used chemical blowing agents (for example, azodicarbonamide foaming agents), the resulting foams show improvement effects in terms of shrinkage, sink marks, warpage, etc. When the agent thermally decomposes and generates gas, a large amount of decomposition heat is generated. As a result, the viscosity at the melting temperature decreases, making it easier for decomposed gas to escape to the surface of the molded product, causing surface roughness.
In the composition of the present invention, the oxyacid and the inorganic carbonate, which are blowing agents, react inside the molten resin during heat molding, generating gas, and since the heat of reaction is small, the viscosity of the molten resin is further reduced. It is inferred that this results in less gas leaking to the surface of the molded product, that only the inside of the molded product foams, a surface skin layer is formed, and that a molded product with a beautiful surface can be obtained. The composition of the present invention does not have the above-mentioned drawbacks,
Moreover, since it has various effects, it can be used in a wide variety of fields. Typical uses are shown below. (1) Thick injection molded products such as handles and handles (2) Injection molded products that have many ribs and cause sink marks with ordinary crystalline olefin resin (3) Extrusion molded products such as thick plates Specific Description (A) Crystalline Olefin Resin Generally, the crystalline olefin resin used in the present invention is homopolymerized or copolymerized with ethylene or α-olefin having at most 12 carbon atoms. Here are the things you can get by. Typical examples of these crystalline olefin resins include high-density polyethylene, medium-density polyethylene, chain low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, and propylene-ethylene random polyethylene. Polymers, propylene-ethylene block copolymers, poly(butene-1) and poly(4)
-methylpentene-1). Among the crystalline olefin resins, high-density polyethylene and medium-density polyethylene are produced by ethylene homopolymerization using a so-called Ziegler catalyst or a Phillips catalyst, or by polymerizing ethylene with the α
- olefin (the copolymerization ratio of α-olefin is generally at most 15% by weight). The molecular weight of these polyethylenes is generally 10,000 to 1,000,000, and preferably 20,000 to 500,000. Further, the density is 0.935 to 0.980 g/cm ³ . Furthermore, high-pressure low-density polyethylene is obtained by homopolymerizing ethylene or copolymerizing ethylene and a vinyl compound (copolymerization ratio of 10% by weight or less) using a so-called free radical catalyst. Generally 0.900 to 0.935
g/ ^cm3 . Further, the molecular weight is usually 10,000 to 500,000, and particularly preferably 20,000 to 200,000. Other crystalline olefin resins are those obtained using a so-called Ziegler-Natsuta catalyst. Among these crystalline olefin resins, chain low density polyethylene has ethylene and 5
It is obtained by copolymerizing ~35% by weight of the above α-olefin, and its density is usually 0.900~0.935g/cm ³ . Isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene random copolymers and propylene-ethylene block copolymers are prepared by homopolymerizing propylene or copolymerizing propylene with at most 20% by weight of ethylene. It is something that can be obtained.
The molecular weight of these crystalline olefin resins is
Usually 10,000 to 500,000, especially 20,000 to 40
10,000 is desirable. Poly(butene-1) and poly(4-methylpentene-1) are obtained by homopolymerizing butene-1 or 4-methylpentene-1. In carrying out the present invention, high density polyethylene, medium density polyethylene, linear low density polyethylene, isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene random copolymer and propylene-ethylene block copolymer are suitable. . In producing the crystalline olefin resin composition of the present invention, only one type of these crystalline olefin resins may be used, or two or more types may be used in combination. Furthermore, a small amount of amorphous resin and/or rubber-like material may be blended to the extent that the excellent resin properties originally possessed by these crystalline olefin resins are not impaired. Generally, the proportion of these amorphous resins and rubbery substances is at most 40% by weight. (B) Oxyacid The oxyacid used in the present invention is
Aliphatic, alicyclic and aromatic saturated or unsaturated oxyacids having a total carbon number of 2 to 30 and 1 to 10 hydroxy groups are common. In addition, the carboxylic acid group is usually 1 to 10
It has individuality. Among these oxyacids, those having a total carbon number of 2 to 10, 1 to 3 hydroxyl groups, and 1 to 4 carboxyl groups are particularly preferred. Representative examples of suitable oxyacids include glycolic acid,
Mention may be made of lactic acid, hydroacrylic acid, alpha-oxybutyric acid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid, oxybenzoic acid, gallic acid, mandelic acid and tropic acid. In producing the crystalline olefin resin composition of the present invention, only one type of oxyacid may be used, or two or more types may be used in combination. (C) Inorganic carbonate Furthermore, the inorganic carbonate used in the present invention is ammonium or A group, B group, A
carbonates of Group B, Group B, or Group metals. Typical examples of this inorganic carbonate are:
Ammonium carbonate, ammonium hydrogen carbonate, lithium carbonate, lithium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, sodium potassium carbonate, potassium carbonate, cesium carbonate, copper carbonate
(1), silver carbonate, beryllium carbonate, magnesium carbonate, potassium magnesium hydrogen carbonate, potassium magnesium carbonate, magnesium carbonate hydroxide,
Calcium carbonate, strontium carbonate, barium carbonate, zinc carbonate, cerium carbonate, thallium carbonate, carbonate (), chromium carbonate, manganese carbonate,
Iron carbonate (FeCO ₃ ), iron carbonate (FeCO ₃ H ₂ O),
Examples include cobalt carbonate and nickel carbonate. In producing the crystalline olefin resin composition of the present invention, one kind of the inorganic carbonate may be used, or two or more kinds may be used in combination. (D) Blending ratio When producing the crystalline olefin resin composition of the present invention, the blending ratio of oxyacid and inorganic carbonate in the composition is determined as the total amount.
It is 0.02-10.0% by weight. If the total proportion of the oxyacid and inorganic carbonate in the composition is 0.02% by weight, the effects of the present invention cannot be fully exhibited. On the other hand, even if it is blended in an amount exceeding 10.0% by weight, not only is it not possible to further improve the effects of the present invention, but also the good properties inherent to the crystalline olefin resin are impaired. Further, the ratio equivalent of the inorganic carbonate to the oxyacid is 0.9 to 1.1 per 1 of the oxyacid. If the ratio of inorganic carbonate to 1 equivalent of oxyacid is less than 0.9 equivalents, the amount of inorganic carbonate to oxyacid is not sufficient, and the reaction between the two will not take place sufficiently, resulting in a good foaming state. A molded product cannot be obtained. On the other hand, if the amount exceeds 1.1 equivalent, the amount of oxyacid blended with respect to the inorganic carbonate is insufficient, and a molded product having a good foamed state cannot be obtained for the same reason as above. (E) Mixing method The crystalline olefin resin composition of the present invention is
It can be produced by uniformly mixing a crystalline olefinic resin, an oxyacid, and an inorganic carbonate. As a mixing method, dry blending may be performed using a mixer such as a Henschel mixer or a ribbon mixer that is commonly used in the olefin resin industry.
It can be obtained by melt-kneading using a mixer such as a Banbury mixer, kneader, roll mill, or screw extruder, but melt-kneading using an extruder is generally preferred. At this time, a uniform composition can be obtained by dry blending in advance and melt-kneading the resulting composition (mixture). In this case, it is generally obtained by melt-kneading and then forming into pellets. When producing this composition, all the ingredients may be mixed at the same time, or some of the ingredients may be mixed and the remaining ingredients may be sequentially added to the mixture while mixing. Alternatively, a so-called masterbatch may be prepared with part of the crystalline olefin resin and part or all of the oxyacid and inorganic carbonate, and the remaining ingredients may be added to and mixed with this masterbatch. It goes without saying that these must be mixed at a temperature below which the oxyacid and inorganic carbonate do not decompose thermally. When producing the crystalline olefin resin composition of the present invention, stabilizers against oxygen and heat, metal deterioration inhibitors, nucleating agents for foaming, which are commonly used in the field of crystalline olefin resins,
Fillers, lubricants and flame retardants may also be added. (F) Molding method, etc. Molding methods include extrusion molding, injection molding, and press molding. Furthermore, molding methods commonly used in the field of crystalline olefin resins, such as stamping, press molding using an extruded sheet, and vacuum forming, may also be applied. It goes without saying that both melt-kneading and molding to produce the crystalline olefin resin composition of the present invention must be carried out at a temperature equal to or higher than the melting point of the crystalline olefin resin used. , these must be carried out at temperatures below which thermal deterioration does not occur. From the above, the melt-kneading temperature and molding temperature are generally 120 to 350°C. The kneading temperature is preferably low, and the molding temperature is preferably relatively high. Particularly preferred is 200 to 300°C. moreover,
If the composition of the present invention is molded at 120° C. or lower, the oxyacid and the inorganic carbonate may not react, making it impossible to obtain a good molded product. On the other hand, if melt-kneaded or molded at temperatures above 350°C, the crystalline olefin resin may undergo thermal deterioration, the oxyacid and inorganic carbonate may react rapidly, or the oxyacid and inorganic carbonate may undergo thermal decomposition. be. As a result, not only the composition and molded product become colored and the physical properties of the resin deteriorate, but also when molded at 350°C or higher,
Due to the large temperature difference between the molding temperature and the room temperature, dimensional changes, sink marks, warpage, etc. of the molded product occur, resulting in adverse effects. As mentioned above, the composition of the present invention has excellent processability, so it can be molded into various shapes by the above-mentioned molding method and used in many ways, but it is especially suitable for thick molded products and It is promising when producing molded products with many ribs. [] Examples and Comparative Examples The present invention will be explained in more detail below using Examples. In addition, in the examples and comparative examples, melt
The index (hereinafter referred to as "MI") is JIS K-
According to 6760, temperature is 190℃ and load is 2.16
Measured under Kg conditions. In addition, the melt flow index (hereinafter referred to as "MFI") is based on JIS K-
According to 6758, temperature is 230℃ and load is 2.16
Measured under Kg conditions. Furthermore, dimensional stability tests were carried out using injection molding with a mold size of 6.50 mm at a temperature of 230°C for crystalline propylene-based resins and 230°C for crystalline ethylene-based resins. did. The thickness of each obtained molded product was actually measured and evaluated. Example 1 Isotactic propylene homopolymer (MFI 8.0 g/10 min, hereinafter referred to as "PP") powder 100
Part by weight, 0.1 part by weight of citric acid powder and 0.1 part by weight of anhydrous sodium carbonate powder were mixed for 3 minutes using a Henschel mixer. The resulting mixture was injection molded to produce a molded product. The thickness of this molded product is 6.48 mm, and it not only has excellent dimensional stability, but also has a surface condition in which only the inside of the molded product is foamed, a surface skin layer is formed, and no sink marks or warpage can be observed. The appearance was good, that is, the appearance was beautiful. Examples 2 to 5 100 parts by weight of PP used in Example 1 and the oxyacid and inorganic carbonate shown in Table 1 were added, respectively.
A mixture was prepared in the same manner as in Example 1 using 0.1 part by weight.
Each of the obtained mixtures was injection molded to produce molded products. Table 1 shows the thickness of each molded product. It should be noted that all of the molded products obtained had excellent surfaces, with no sink marks or warpage, that is, beautiful appearance. Examples 6 to 8 Instead of the PP used in Example 1, high ^- density polyethylene (M.
I.8.0g/10min, hereinafter referred to as "HDPE"), density is
Crystalline linear low-density polyethylene (MI 4.0 g/10 min, butene content 17.2% by weight, hereinafter referred to as "L-LDPE") with a density of 0.923 g/cm ³ and crystalline propylene-ethylene block copolymer ( MFI8.0
A mixture was produced in the same manner as in Example 1, except that 100 parts by weight of each block copolymer (100 g/10 min, ethylene content 8.5% by weight, hereinafter referred to as "block copolymer") was used. Injection molding was performed using each of the obtained mixtures. As in Example 1, each molded product obtained had almost no warpage or sink marks, and had a good surface condition. Table 2 shows the thickness of the molded product obtained.

【table】

[Table] Examples 9 to 11 100 parts by weight of PP used in Example 1, as well as citric acid powder and anhydrous sodium carbonate powder whose respective blending amounts are shown in Table 3, were mixed in the same manner as in Example 1. Each of the obtained mixtures was injection molded in the same manner as in Example 1 to produce molded products. Table 3 shows the thickness of each molded product. It should be noted that all of the molded products obtained had excellent surfaces, with no sink marks or warpage observed, that is, they were beautiful.

[Table] Comparative Example 1 When injection molding was carried out in the same manner as in Example 1 using only the PP used in Example 1, an injection molded product with large sink marks was obtained. The thickness of this injection molded product was 5.30 mm. Comparative Example 2 0.2 to 100 parts by weight of PP used in Example 1
Parts by weight of azodicarbonamide were mixed in the same manner as in Example 1. When the resulting mixture was injection molded in the same manner as in Example 1, it foamed, and although no sink marks or warpage was observed, a molded product with a rough surface was obtained. The thickness of this molded product is 6.45mm
It was hot.

Claims (1)

[Claims] 1. A composition comprising (A) a crystalline olefin resin, (B) an oxyacid, and (C) an inorganic carbonate, where the oxyacid and the inorganic carbonate account for the entire composition. Percentage is as total amount
1. A crystalline olefin resin composition characterized in that the amount of the inorganic carbonate is 0.02 to 10.0% by weight, and the ratio of the inorganic carbonate to the oxyacid is 1:0.9 to 1:1.1 as an equivalent.