JPH04146963A - Blow molded polyamide article - Google Patents

Abstract

PURPOSE:To produce, with an excellent moldability, the title article excellent in low-temp. impact strength by mixing a polyamide resin with a specific modified block copolymer to give an intimate mixture having a specified apparent melt viscosity and molding the mixture. CONSTITUTION:50-98wt.% polyamide resin is mixed with 50-2wt.% modified block copolymer obtd. by grafting 0.05-5 pts.wt. alpha,beta-unsatd. carboxylic acid or driv. thereof onto 100 pts.wt. block copolymer comprising a vinyl arom. compd. polymer block and an olefin compd. polymer block with an unsaturation of 20% or lower and having a vinyl arom. compd. content of 10-90wt.%, thereby giving an intimate mixture having such an apparent melt viscosity that apparent melt viscosities (P), mua1, mua10, and mua100, measured at a const. temp. 20 deg.C higher than the m.p. (Tm) of the polyamide resin (Tm+20 deg.C) at shear rates of 1, 10, and 100 (sec<-1>), respectively, satisfy formulas: 2000000>=mua10>=2000 and mua1/mua100>=3.3. The mixture is blow molded.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to polyamide-based plastic blow-molded products with improved melt viscosity properties and impact resistance properties. An impact-resistant product made by blending a modified block copolymer in which an unsaturated carboxylic acid or a derivative thereof is kraft to form a close mixture with improved apparent melt viscosity (hereinafter simply referred to as melt viscosity) properties. This article relates to excellent polyamide blow molded products.

<Prior art> When performing blow molding, when forming a parison from molten polymer, it is necessary to sufficiently maintain the shape of the polymer melt extruded from the die and to obtain uniformity in dimensions and wall thickness of the molded product. It is desirable to have a high melt viscosity, which is particularly important for obtaining blow-molded products for large-capacity containers. Furthermore, although polyamide is considered to be a relatively strong material, its toughness and impact resistance vary greatly depending on temperature and moisture content. The material becomes quite brittle when it is completely dry or at low temperatures.Therefore, in order to obtain polyamide blow molded products that have practical value as commercial products, it is important to overcome the need to improve impact resistance at low temperatures and low moisture absorption. It is one of the insults.

Although polyamide has various excellent properties, it is currently not fully utilized, especially as blow molded products, due to the drawbacks mentioned above. The industry is eagerly awaiting the emergence of blow-molded products that have a high melt viscosity and excellent impact resistance at low temperatures and low moisture absorption.Polyamide is already widely used in blow-molded products. This is known and the inventors have already carried out 2.3 studies on methods for producing polyamides with melt viscosity properties suitable for the production of large-sized blow molded articles. Specifically, a method in which a polyfunctional epoxy compound containing a vinyl epoxy group and a vinylene epoxy group is added to polyamide, mixed and heated and melted (Japanese Patent Publication No. 48-7509), or a method in which trimesic acid is added during polymerization of a monomer for polyamide such as lactam. Method of polymerization by adding diamine salt
No. 0-2790, No. 50-2791, No. 50
3193, 50-104297, etc.) is to introduce a branched chain into a polyamide molecule.

The branched polyamide produced by this method has good viscosity stability and high melt viscosity, properties suitable for obtaining blow molded products, and has improved impact resistance, especially at low temperatures. A blow molded product with excellent impact resistance at low moisture absorption could not be obtained.

In order to solve this drawback, the present inventors have revealed that an intimate mixture of polyamide and ethylene ionomer and/or carboxy-modified nitrile rubber is effective (Japanese Patent Publication No. 55-41659).

<Problems to be Solved by the Invention> However, in recent years, as automobile parts have become lighter and more plastic has been used, and blow molding technology has improved, the properties required of plastics have become even higher. In other words, there is a desire for materials with higher low-temperature impact resistance and better thermal stability. Although impact resistance modifiers such as ethylene ionomer resins and/or carboxy-modified nitrile rubbers shown in the previous examples have suitable properties for obtaining blow molded products when mixed with polyamides, Further improvements are desired in terms of low-temperature impact resistance and thermal stability.

As a polyamide composition having excellent impact resistance at low temperatures, for example, an intimate mixture of polyamide and a modified block copolymer grafted with an α,β-unsaturated carboxylic acid or a derivative thereof can be used. It is known that the material has much better low-temperature impact resistance than an intimate mixture with carboxy-modified nitrile rubber and/or carboxy-modified nitrile rubber (Japanese Patent Publication No. 6344784).
.

However, there is no disclosure of a blow-molded product with excellent moldability and low-temperature impact strength.

Therefore, the present inventors have developed a method for achieving good blow molding by controlling the melt viscosity of a mixture of polyamide and a modified block copolymer in which α, β-unsaturated carboxylic acid or its derivative has been crafted into a specific range. The present invention was developed based on the discovery that the present invention can provide the following properties.

Means for Solving the Problems> That is, the present invention comprises: (a) 50 to 98% by weight of polyamide; (b) a vinyl aromatic compound polymer block and an olefin compound polymer block having a degree of unsaturation not exceeding 20%; obtained by grafting 0.05 to 5 parts by weight of an α,β-unsaturated carboxylic acid or a derivative thereof to 100 parts by weight of a block copolymer having a vinyl aromatic compound content of 10 to 90% by weight. Shear rate 1 measured at a constant temperature (Tm+20°C) whose apparent melt viscosity is 20°C higher than the melting point (Tm) of the polyamide resin. .10.
A polyamide blow molded product is characterized in that it satisfies the following formulas (I) and (II), where the apparent melt viscosity (voice) at 100 (sec-1) is μ, 1, μ, 1o, μaloo. This is what we provide.

2000000≧μm1゜≧2000 (I)μ6,
/μaloo≧3.3 (II) or less,
The present invention will be described in detail.

Polyamides that can be used in the present invention are not particularly limited, and include ethylenediamine, hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2.
Aliphatics such as 4- and 2,44-trimethylhexamethylene diamine, 13- and 1,4-bis(aminomethyl)cyclohexane, bis(4,4-aminocyclohexyl)methane, meta- and para-xylylene diamine,
Polyamides derived from alicyclic or aromatic diamines and aliphatic, alicyclic or aromatic dicarboxylic acids such as adipic acid, speric acid, sebacic acid, cyclohexanedicarphonic acid, terephthalic acid or isophthalic acid, ε-caprolactam,
Polyamide obtained by ring-opening polymerization of lactams such as ω-dodecalactam, 6-aminocaproic acid, 11-
Polyamides derived from aminoundecanoic acid, 12-aminododecanoic acid, etc., and copolyamides thereof,
It is a mixed polyamide. Specifically, polycaproamide (
Nylon-6), polydodecamide (nylon-12)
, polyhexamethylene adipamide (nylon-66),
Polyhexamethylene diamine (nylon-610>, polyhexamethylene terephthalamide (nylon-6T),
Polyhexamethylene isophthalamide (nylon-6I)
), these copolymers such as nylon 6/66,
Nylon 6/610, Nylon 6/12, Nylon 6/
66/61.0, nylon 66/12, nylon 6/6
6/610/12, nylon 6/6T, nylon 66/
6T, nylon 6/6I, nylon 66/6I, nylon 6/61/6T, nylon 66/61/6T and mixtures thereof, and the like are useful. Polyamide polymerization methods include melt polymerization, interfacial polymerization, solution polymerization, boundary polymerization, solid phase polymerization, and combinations thereof.

Generally, melt polymerization is most suitable. The polymer may also be obtained by anionic polymerization, especially in the case of polyamide raw materials or lactams.

Furthermore, there is no restriction on the degree of polymerization of the polyamide used here, and it usually has a relative viscosity (1 g of polymer is mixed with 98% concentrated sulfuric acid 100%
Dissolved in ml and measured at 25°C.

The same applies hereinafter) can be selected from a polyamide having a value within the range of 2.0 to 6.0.

The modified block copolymer of the present invention is synthesized, for example, as follows. That is, the degree of unsaturation in the conjugated diene portion of the block copolymer composed of a vinyl aromatic compound copolymer block and a polymer block mainly composed of a conjugated diene compound is selected so as not to exceed 20%. hydrogenated to form a block copolymer consisting of a vinyl aromatic compound polymer block and an olefin compound polymer block with an unsaturation degree not exceeding 20%, and then α, β-
A modified block copolymer is obtained by addition reaction with an unsaturated carboxylic acid or its derivative.

The above block copolymer before hydrogenation contains at least one vinyl aromatic compound polymer block, preferably two or more, and at least one polymer block mainly composed of a conjugated diene compound. . Here, the polymer block mainly composed of a conjugated diene has a weight ratio of a vinyl aromatic compound and a conjugated diene compound of O/100 to 50.
150, preferably in the composition range from O/Zoo to 40/60, and the distribution of the vinyl aromatic compound in this block is random or tapered (the monomer component increases or decreases along the molecular chain). ),
It may be in a block shape or in any combination thereof. In addition, in the block copolymer before hydrogenation in the present invention, 50% by weight of the vinyl aromatic compound is contained in the transition region between the vinyl aromatic compound polymer block and the polymer block mainly composed of a conjugated diene compound. Although there may be a copolymer portion of a vinyl aromatic compound and a conjugated diene compound exceeding 100%, such a polymer portion shall be included in the polymer block mainly composed of the conjugated diene compound.

In the above block copolymer, the weight ratio of the content of the vinyl aromatic compound and the content of the conjugated diene compound is 10/
The range is 90 to 90/10, preferably 20/80 to 85/15.

As the vinyl aromatic compound constituting the block copolymer before hydrogenation, one or more types are selected from styrene, α-methylstyrene, vinyltoluene, etc.,
Among them, styrene is particularly preferred. Further, as the conjugated diene compound, one or more types are selected from butadiene, isoprene, 1,3-pentadiene, etc., and butadiene and/or isoprene is particularly preferred. The above block copolymer has a number average molecular weight of 20,000
~ 500,000, and the molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably in the range of 1.05 to 10, and the molecular structure of the block copolymer is linear,
It may be branched, radial, or a combination thereof. Furthermore, when butadiene is used as the conjugated diene compound in the block copolymer, the amount of 1.2 bonds in the microstructure of the butadiene moiety is preferably in the range of 10% to 80%. When it is necessary to give the modified block copolymer rubber elasticity, the amount of 1.2 bonds is 35 to 5.
A range of 5% is particularly preferred.

In the case where the above block copolymer contains two or more blocks mainly composed of vinyl aromatic compound blocks or conjugated diene compounds, each block may have the same structure, and the monomer component content and their Each structure such as the distribution in the molecular chain, the molecular weight of the block, and the microstructure may be different.

The above block copolymer is usually obtained by anionic living polymerization using an organic lithium compound as a catalyst and a vinyl aromatic compound and a conjugated diene compound as monomers in an inert hydrocarbon solvent. Even if it is legally obtained, it can be used as long as it falls within the above range. Furthermore, it is also possible to use not only one type of block copolymer but also a mixture of two or more types.

The above block copolymer can be prepared by a known method, for example,
By hydrogenating according to the method described in Publication No. 2-8704, not more than 20% of the aromatic double bonds of the vinyl aromatic compound and at least 80% of the aliphatic double bonds of the conjugated diene compound block are hydrogenated. The added partially hydrogenated block copolymer is synthesized.

The degree of unsaturation of a conjugated diene compound block as used in the present invention refers to the proportion of carbon-carbon double bonds contained in the conjugated diene compound block, and this is determined by nuclear magnetic resonance absorption spectrum (NMR), infrared rays Absorption spectrum (IR)
It is measured by instrumental analysis such as, chemical analysis such as iodometry.

The partially hydrogenated block copolymer is then modified by addition reaction with an alpha, beta unsaturated carboxylic acid or derivative thereof. Examples of α,β-unsaturated carboxylic acids or derivatives thereof to be added include maleic acid, maleic anhydride, fumaric acid, itaconic acid, acrylic acid, crotonic acid, cis-4 cyclohexane 1,2-dicarboxylic acid and its anhydride. thing,
Examples include maleimide. Among them, maleic anhydride is particularly preferred.

The above-mentioned modified block copolymers can be produced by adding α, β-unsaturated carboxylic acids or derivatives thereof to partially hydrogenated block copolymers in solution or in the melt, with or without the use of radical initiators. It can be obtained by adding A preferred method for producing these modified block copolymers is, for example, a method in which an unmodified block copolymer is reacted with an α,β-unsaturated carboxylic acid or a derivative thereof in the presence of a radical initiator in an extruder. .

The amount of α,β-unsaturated carboxylic acid or its derivative added to the block copolymer is 0.05 to 5 parts by weight, particularly preferably 0.1 to 3 parts by weight, per 100 parts by weight of the block copolymer. .

If the added amount is less than 0.805 parts by weight, when made into a composition, there is only a slight improvement compared to an unmodified conjugated diene polymer, and even if the added amount exceeds 5 parts by weight, there is no improvement compared to less than that. Almost no effect can be seen. α, β- used in the present invention
Unsaturated carboxylic acids or derivatives thereof can be used not only alone but also as a mixture of two or more.

Suitable modified block copolymers include a series of resins sold under the trade name Tuftic by Asahi Kasei Kogyo, such as Tuftic M1911 M19.
13, M1943, M1953, or a series of resins sold under the Kraton trademark by Shell Chemical Co., Ltd., such as Kraton FG1901X. These modified block copolymers can be used not only as a single type but also as a mixture of two or more types.

The polyamide blow-molded article of the present invention contains 2 to 50% by weight of the modified block copolymer, particularly preferably 1% by weight, based on the polyamide.
It is composed of a material formed by intimately mixing 0 to 40 parts by weight. If the amount of the modified block copolymer is less than 2% by weight, not only will the effect of increasing the shear rate dependence of the melt viscosity of the mixture decrease noticeably, but it will also become impossible to obtain a blow molded product with excellent impact resistance. . On the other hand, if the amount of the modified block copolymer blended is 50% by weight or more, the characteristics of polyamide will not be exhibited, and the original purpose of producing a polyamide-based plastic blow molded product will be different, which is not preferable.

The melt viscosity can be easily controlled by the relative viscosity of the polyamide used and the amount of the modified block copolymer. In other words, for polyamides with high relative viscosity, the amount of modified PRO-NK copolymer may be small, and conversely, for polyamides with low relative viscosity, the amount of modified PRO-NK copolymer may be increased. There is a need to. Furthermore, the melt viscosity is determined by the blending amount of polyamide and modified block copolymer so as to obtain the required parison length depending on the shape of the blow-molded product.

If the melt viscosity is less than 2,000 poise, the parison will sag, making it impossible to obtain a good molded product.On the other hand, if the melt viscosity is greater than 2ooo or ooo poise, the load on the molding machine will increase, resulting in poor moldability. This is not good as it will damage the

In addition, the formula (I[> is a formula expressing the magnitude of the shear rate dependence of melt viscosity, and is the ratio of the melt viscosity in the low shear rate region to the melt viscosity in the high shear rate region, and the magnitude of the shear rate dependence is The melt viscosity characteristic is expressed by the formula (
If II) is not satisfied, it is not preferable because the change in melt viscosity with respect to shear rate is small and good blow molding cannot be performed. The ratio of melt viscosity values (μ21
/μ,,. The upper limit of 0) is not particularly limited, but in view of the performance of the molding machine, a value of about 20 is a common sense upper limit value.

The method of mixing polyamide and modified block copolymer is not particularly limited, and any commonly known method can be used. However, after uniformly mixing the pellets, powder, or pieces of both with a high-speed stirrer, sufficient kneading ability is required. A method of melt-kneading using an extruder is suitable. It is also possible to use a method in which the uniformly mixed pellets are not kneaded in advance in an extruder, but are directly kneaded in a molding machine during blow molding, and then molded. There are no restrictions regarding the blow molding method, and conventionally known methods can be used. That is, for boat fishing, a parison may be formed using a normal blow molding machine, and then blow molding may be carried out at an appropriate temperature.

In order for the blow-molded article of the present invention obtained as described above to have excellent impact strength, both molds as constituent components must be intimately mixed with each other. A modified block copolymer is dispersed in the form of particles in a polyamide matrix phase. In order to obtain a molded article with improved impact strength, especially excellent impact resistance at low temperature and low moisture absorption, it is preferable that the dispersed particle size is 10 microns or less.

These mixtures further possess the following characteristics:

(1) The amount of the modified block copolymer to be blended to increase the viscosity of the mixture can be smaller than the amount of the ionomer and/or carboxy-modified nitrile rubber.

(2) The shear and velocity dependence of the melt viscosity of the mixture is greater than that of the original polyamide alone, and exhibits properties suitable for blow molding.

(3) In the mixture, the two molds as constituent components are closely mixed with each other, and the molded product obtained by molding the mixture has high impact resistance strength at low temperature and low moisture absorption.

etc.

Other ingredients such as pigments, antioxidants, weathering agents, crystallization promoters, reinforcing materials, heat resisting agents, etc. may be added to the blow-molded product of the present invention as long as they do not impair its moldability or physical properties. be.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Relative viscosity obtained by melt polymerizing ε-caprolactam: 4.
30. 20% by weight of "Toughtic" M1913 (manufactured by Asahi Kasei Corporation) was added and mixed to polycaproamide having a melting point of 225°C, and the mixture was melt-kneaded in a 3011f 1-diameter extruder set at 250°C, and then pelletized. After drying this pellet in vacuum, it was dried at a shear rate of 1 se at a temperature of 245°C using a melt inflator manufactured according to ASTM-D-1238.
The melt viscosity of this pellet at c-', 10 sec-', and 100 sec-' (μ, 1, μ, 1, respectively)
゜, μ, 1゜. ) was measured. The result is μ, 1=8X
10' poise, μalo=3×105 poise, and μ
, 1°. = sx i o'poise, and these values satisfied formulas (I> and (II)).

Next, the pellets obtained here were molded using a blow molding machine with an extruder having a diameter of 40 mm and an outer diameter of 20 mm and a wall thickness of 2 m at 250°C.
When a parison was formed and a reagent bottle of 500011 was molded, the state of the parison was observed, and no sagging was observed, indicating that blow molding could be carried out extremely well and a molded product with uniform wall thickness could be obtained. was completed.

The pellets obtained here were also injection molded and their mechanical properties were measured. The results are shown in Table 1.

table II No NB breakage.

Comparative Example 1 “Surlyn A” 1 instead of “Toughtic” in Example 1
706 (ionomer resin manufactured by Du Bonn Co., USA) at 20
A composition of polycabramide and ionomer resin was obtained in the same manner as in Example 1 except that the weight percentages were added and mixed. The shear rate of this composition at a temperature of 245°C is 1 sec-', 10
The melt viscosity at sec-' and 100 sec' is μm+=2X105, μ,1°-7,5X10' and μmrao''2.5X10', and the composition of Example 1 has a greater thickening effect. I got angry. Also Il
As shown in Table 2, the mechanical properties of the composition of Example 1 were superior, especially in terms of impact resistance.

Table 2 Examples 2 to 5 The same operations as in Example 1 were performed except that the types and blending amounts of polyamide, modified block copolymer, etc. were changed as shown in Table 3. The melt viscosity of these mixtures satisfies both formulas (I) and (II>), and in both cases, the shape retention of the parison during blow molding is extremely good, and a blow molded product with a uniform wall thickness can be easily obtained. Furthermore, each composition was excellent in terms of impact resistance.These results are shown in Table 3.

<Effects of the invention> It is now possible to manufacture blow-molded products with desirable properties that could not be achieved with existing single materials, which can be used in a wide range of applications as engineering plastics, and has great industrial value. .

Patent Consultant Toshi Co., Ltd.

Claims (1)

Scope of Claims: (a) 50 to 98% by weight of polyamide (b) Consisting of a vinyl aromatic compound polymer block and an olefin compound polymer block with a degree of unsaturation not exceeding 20%, containing a vinyl aromatic compound Modified block copolymer 50-2 obtained by grafting 0.05 to 5 parts by weight of an α,β-unsaturated carboxylic acid or a derivative thereof to 100 parts by weight of a block copolymer having an amount of 10 to 90% by weight. % by weight at a shear rate of 1, 10, 1, measured at a constant temperature (Tm+20°C) whose apparent melt viscosity is 20°C above the melting point (Tm) of the polyamide resin.
The apparent melt viscosity (poise) at 00 (sec^-^1) is μ_a_1, μ_a_1_0, μ_a_1_0
A polyamide blow-molded product characterized by satisfying the following formulas (I) and (II) when _0. 2000000≧μa_1_0≧2000(I)μ_
a_1/μ_a_1_0_0≧3.3(II)