JPS5811533A - Crystalline olefin resin composition - Google Patents

Abstract

PURPOSE:To prepare the titled comosition having excellent moldability and giving molded article having excellent dimensional stability and surface appearance, by compounding a crystalline olefin resin with specific amounts of hydroxy acid and an organic carbonate. CONSTITUTION:The objective composition is obtained by melting and mixing (A) a crystalline olefin resin (e.g. high-density polyethylene, etc. having a molecular weight of usually 10,000-500,000), (B) a hydroxy acid (a 2-30C aliphatic, alicyclic or aromatic acid having 1-10 hydroxyl groups, e.g. glycolic acid) and (C) an inorganic carbonate (carbonate of ammonium or aIA,IB, IIA, IIB, IVB or VIII group metal, e.g. ammonium carbonate) with a mixer such as Henschel mixer. The amount of the components (B)+(C) is 0.01-40wt% based on the whole composition, and the ratio of (B):(C) is 1:(0.1-10). USE:Thick-walled article, molded article having many ribs, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Objects of the Invention The present invention relates to crystalline olefinic tree candy compositions. In further detail, (A) crystalline olefin resin, (B)
This invention relates to a crystalline olefin resin composition comprising an oxyacid and (C) an inorganic carbonate, and its purpose is to provide a crystalline olefin resin molded article 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 characteristics such as electrical properties and processability, and is used in a wide variety of fields. However, in the process of obtaining a molded article from a molten state, it crystallizes and solidifies, resulting in a much larger change in density than that of non-quality olefin resins. As a result, especially in injection molding, there are disadvantages such as the finished size of the mold becomes small, sink marks occur in thick molded products, and warpage occurs due to the anisotropy of shrinkage rate.

Conventionally, methods to improve these drawbacks include methods of obtaining molded products using special molds, methods of highly filling inorganic materials,
Methods of adding nucleating agents, methods of molding under special molding conditions,
Methods such as adding a conventional chemical blowing agent are used.

However, methods that use special molds limit the design of the molded product, and methods that use a high amount of inorganic material may result in deterioration of physical properties and surface gloss of moldability, or the addition of nucleating agents. The improvement effect is not sufficient with the method of adding a chemical foaming agent, and the method of molding with special molding conditions lengthens the molding cycle, and the method of adding a normal chemical foaming agent may cause foaming on the surface of the molded product. Furthermore, there were other problems (disadvantages) such as roughening of the surface of the molded product.

Based on the above, the present inventors have conducted various searches to obtain molded products of crystalline olefin resin that have these drawbacks and have particularly excellent dimensional stability. , (B) 0 to 100 parts by weight of strong olefin resin
Oxy acid-containing crystalline olefin resin mixture obtained by mixing 01 to 30 parts by weight of oxyacid and (C) 00 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 1 to 30 parts by weight of an inorganic carbonate, and the oxy-acid-containing crystalline olefin resin mixture and the 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 have the above-mentioned problems and have poor dimensional stability. We have previously proposed a composition that can produce excellent molded articles.

l Structure of the Invention Similarly to the above, the present inventors further searched for obtaining a molded product of crystalline olefin resin having particularly excellent dimensional stability, which has the above-mentioned drawbacks, and as a result, (A) Crystalline olefin resin (B) A composition consisting of an oxyacid and a (C1° inorganic carbonate), and the blending ratio of the oxyacid and inorganic carbonate in the entire composition is 0.01 to 40% as a total amount.
% by weight, and the ratio of the inorganic carbonate to the oxyacid is from 1:0, 1 to 1:10 as an equivalent, as described above. The inventors have discovered that the composition has the following problems (defects) and can produce molded articles with excellent dimensional stability, and have arrived at the present invention.

(2) 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) Since the surface condition is good, the appearance is beautiful.

(2) Since the composition has excellent moldability, molded products of various shapes can be obtained.

(3) Because the composition has excellent moldability (processability),
Molded products can be obtained even with a short molding cycle.

(4) Almost no decrease in physical properties is observed.

(5) Almost no whiskers or warpage can be seen in the molded product.

(6) Since the inside of the molded product is foamed, it is lightweight.

The above describes the resin pellet mixture (composition) of the present invention.
When heated and molded at the molding temperature commonly used for olefin resins (120 to 350°C),
This is because only the inside of the resulting molded product is uniformly foamed, so the shrinkage rate is small, there is no so-called warpage or shrinkage, and the surface condition of the molded product is good.

When producing foam using commonly used chemical blowing agents (for example, azodicarbonamide blowing agents),
Although the resulting foam has improved shrinkage, sink marks, warpage, etc., it generates a large amount of decomposition heat when the foaming agent thermally decomposes to generate gas. As a result, the viscosity of the molten resin decreases, making it easier for decomposition gas to escape from the surface of the molded product, resulting in surface roughness. During hot molding, the salt reacts inside the molten resin and gas is generated.Since the reaction heat of the φ is small, the viscosity of the molten resin does not decrease further, and there is little gas leakage to the surface of the molded product, making it easier to mold. It is presumed that only the inside of the object foams, a surface skin layer is formed, and a molded object with a beautiful surface is obtained.

Although the composition of the present invention has the above-mentioned drawbacks, it also has various effects, so that 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 a lot of lippage and sink marks are a problem with ordinary crystalline olefin resins (3) Concave extrusion molded products such as thick plates Details of the invention Explanation (A) Crystalline olefin resin The crystalline olefin resin used in the present invention is generally made by homopolymerizing or copolymerizing ethylene or an α-olefin having at most 12 carbon atoms. You get what you get. 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 fluoropylene-ethylene random. Examples include copolymers, propylene-ethylene block copolymers, poly(butene-1) and poly(4-methylpentene-1).

Among nuclear crystalline olefin resins, high-density polyethylene and medium-density polyethylene are produced by ethylene homopolymerization or copolymerization of ethylene and the α-olefin using a so-called Ziegler catalyst or Phillips catalyst (the copolymerization ratio of α-olefin is (generally at most 15 qb)
By doing so, you can obtain ``Niko''. The molecular weight of these polyethylenes is generally from 10,000 to 1,000,000, preferably from 20,000 to 500,000. Also, density 0.935-0.980
11/cm. Furthermore, high-pressure low-density polyethylene is produced by ethylene homopolymerization or ethylene and vinyl compound (copolymerization ratio 10) using a so-called free radical catalyst.
(wt% or less), and their density is generally 0.900 to 0.93.
51//an. In addition, the molecular weight is usually 10,000 to 5
00,000, 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 is obtained by copolymerizing ethylene and 5 to 35% by weight of the above α-olefin, and its density is usually 0.90 to 35% by weight. , c+as#/α3. In addition, isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene random copolymer and propylene-ethylene block copolymer are homopolymerized propylene or propylene and at most 20%
It is obtained by copolymerizing ethylene with a weight percent of ethylene. The molecular weight of these crystalline olefin resins is usually 10,000 to -500,000, especially 20,000 to -500,000.
Desirably 400,000 to 400,000.

Poly(butene-1) and poly(4-methylpentene-
1) is 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 non-quality 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 non-grade resins and rubbery substances is at most 40% by weight.

(B) Oxyacid Also, the oxyacid used in the present invention is an aliphatic, alicyclic, and aromatic saturated or Unsaturated oxyacids are common.

Further, it usually has 1 to 10 carboxylic acid groups. Among these oxyacids, those having a total number of carbon atoms 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, lactic acid, hydroacrylic acid, alpha-oxybutyric acid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid, oxybenzoic acid, gallic acid, mandelic acid and trobic acid. can be given. 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 In addition, the inorganic carbonate used in the present invention is ammonium or LM group, IB group, IIA group, 11B group, V
It is a carbonate of a group IB or group II metal. Typical examples of these inorganic carbonates include ammonium carbonate, ammonium hydrogen carbonate, lithium carbonate, lithium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate 1, sodium potassium carbonate, potassium carbonate, cesium carbonate, steel carbonate (1), steel 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 (II), chromium carbonate, manganese carbonate ,
Iron carbonate (FeCO3), iron carbonate (FeC03・H2O)
, cobalt carbonate and chive carbonate) r/L/. In producing the crystalline olefin resin composition of the present invention, only one type of inorganic carbonate may be used,
Two or more types may be used in combination.

M) Blending ratio In producing the crystalline olefin resin composition of the present invention, the blending ratio of oxyacid and inorganic carbonate in the composition is 0.01 to 40% by weight as a total amount,
0.01 to 20% by weight is preferred, especially 0.02 to 20% by weight.
10.0% by weight is preferred.

If the total proportion of the oxyacid and inorganic carbonate in the composition is 0.01% by weight, the effects of the present invention cannot be fully exhibited.

On the other hand, even if it is blended in an amount of 40% by weight or more, not only is it not possible to further improve the effects of the present invention, but also the good properties originally possessed by the crystalline olefin resin are impaired.

In addition, the ratio of the inorganic carbonate to the oxyacid is 0.1 to 10 per 1 of the oxyacid, and is 0.6
-1,7 is preferable, 0,7-1,3 is more desirable, and 0.9-1,1 is especially suitable.

The blending ratio of inorganic carbonate to 1 equivalent of oxyacid is 50.
If the amount is less than 1 equivalent, the amount of the inorganic carbonate to the oxyacid is not sufficient, and the reaction between the two will not be carried out sufficiently, making it impossible to obtain a molded product having a good foamed state. On the other hand, if the amount is more than 1O equivalent, the amount of oxyacid blended with respect to the inorganic carbonate is not sufficient, 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 can be produced by uniformly mixing the crystalline olefin resin, oxyacid, and inorganic carbonate. As a mixing method, tri-blending may be performed using mixers such as Henschel mixers and ribbon mixers, which are commonly used in the olefin resin industry, or tri-blending may be performed using mixers such as Banbury mixers, kneaders, roll mills, and screw extruders. Although it can be obtained by melt-kneading using a mixer, it is generally preferable to melt-knead using an extruder. At this time, a homogeneous composite can be obtained by tri-blending in advance and melt-kneading the resulting composition (mixture). In this case, it is generally obtained by melt-kneading and then molding 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. Also,
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 and mixed to 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, fillers, lubricants, etc., which are commonly used in the field of crystalline olefin resins, Materials and flame retardants may also be added.

(F) Molding method Examples of the molding method 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.

In order to produce the crystalline olefin resin composition of the present invention, whether it is melt-kneading or molding, it goes without saying that the process 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 melting cross wire temperature and molding temperature are generally 1
The temperature is 20-350°C. The lower the kneading temperature, the better.
Furthermore, it is desirable that the molding temperature be relatively high. Especially 200
-300 is preferable. Furthermore, 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, when melting or molding 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 will the composition and molded product become colored and the physical properties of the resin will deteriorate, but if molded at 350°C or higher, the large temperature difference between the molding temperature and room temperature will cause dimensional changes, sink marks, and warpage of the molded product. etc. will occur without any negative impact.

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 lip molding. It is promising when producing a large number of molded products.

EXAMPLES EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be explained in more detail with reference to Examples below.

In addition, in the Examples and Comparative Examples, the melt index (hereinafter referred to as "M, ■") is based on JISK-6760.
According to the temperature 190℃ and the load 2.16k
It was measured under the conditions of f. In addition, Melt Flow Index (hereinafter referred to as "MFIJ") is based on JIS K-675.
According to 8, the temperature is 230℃ and the load is 2.16
It was measured under the conditions of kl.

Furthermore, the dimensional stability test was carried out at a temperature of 230°C in the case of crystalline propylene resin, and at a temperature of 230°C in the case of crystalline ethylene resin, each with a mold dimension of 6.
．． Injection molding was performed using 50n.

The thickness of each obtained molded product was actually measured and evaluated.

Example 1 Isotactic propylene homopolymer (MFI8, (
1/10 minutes, 100 parts by weight of powder [hereinafter referred to as PPJ],
0.1 parts by weight of citric acid powder and 0.1 parts 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 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 surface condition was good, that is, the appearance was beautiful.

Examples 2 to 5 A mixture was prepared in the same manner as in Example 1 using 100 parts by weight of PP used in Example 1 and 0.1 parts by weight each of the oxyacid and inorganic carbonate shown in Table 1. Each of the obtained mixtures was injection molded to produce molded products. Table 1 shows the thickness of each molded product. In addition, each molded product obtained is
No sink marks or warpage could be observed in any of them, and the surfaces were excellent, that is, the appearance was beautiful.

Examples 6 to 8 Instead of PP used in Example 1, PP with a density of 0.
High density polyethylene (M,
1.8.0 #/10 minutes, hereinafter referred to as rHDPEJ),
Crystalline linear low density polyethylene (M, I, 4.0117
10 minutes, butene-1 content 17.2% by weight, hereinafter "L"
-LDPEJ) and crystalline propylene-
Ethylene block copolymer (MFI s, og/l.

A mixture was produced by mixing in the same manner as in Example 1, except that 100 parts by weight of each block copolymer was used (with an ethylene content of 8.5% by weight, hereinafter referred to as "block copolymer"). 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 1 Table 2 Examples 9 to 11 100 parts by weight of PP used in Example 1 and 3
Citric acid powder and 9um carbonate anhydride powder, the amounts of which are shown in the table, 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, that is, beautiful surfaces.

Table 3 Comparative Example 1 When injection molding was performed in the same manner as in Example 1 using only the PP used in Example I, an injection molded product with large sink marks was obtained. The thickness of this injection molded product is 5.3011
It was +l.

Comparative Example 2 In the same manner as in Example 1, 100 parts by weight of PP used in Example 1 was mixed with 0.2 parts by weight of azodicarbonamide. When the resulting mixture was injection molded in the same manner as in Example 1, it foamed, and although no molding or warping was observed, a molded product with a rough surface was obtained. The thickness of this molded product was 6°4511 DI.

Patent applicant: Showa Denko Co., Ltd. Agent: Patent Attorney Sei Kikuchi

Claims (1)

[Scope of Claims] A composition consisting of (A) a crystalline olefin resin, (B) an oxyacid, and (C) an inorganic carbonate, and the proportion of the oxyacid and the inorganic carbonate in the total composition is is 0.01 to 40 as the total amount
% by weight, and the ratio of the inorganic carbonate to the oxyacid is from 1:0.1 to 1:10 as equivalent.