JPH0414134B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyamide resin composition that has excellent rigidity, low-temperature impact resistance, salt water resistance, and moldability. Polyamide resin is expected to be in great demand as an engineering plastic due to its excellent physical properties. However, performance such as low-temperature impact resistance, water resistance, and salt water resistance is not sufficient, and improvements are desired. For example, as a method of improving impact resistance such as Izotsu impact strength,
Publication No. 12546, Japanese Patent Publication No. 1983-44108, Japanese Patent Publication No. 1983
Prior art documents such as JP-A-9661 and JP-A-55-9662 describe modified α-olefin-based elastic materials such as polyamide resins and ethylene/α-olefin copolymers grafted with α,β-unsaturated carboxylic acids. Methods of blending polymers have been proposed. In all of the compositions proposed in these prior art documents, when impact resistance such as Izot impact strength is improved, the rigidity decreases significantly, and furthermore, the falling weight impact strength at low temperatures is insufficient. The drawback is that it is difficult to obtain actual molded products with high rigidity and high impact resistance. Furthermore, these compositions often have excessively low melt fluidity, and depending on the molding method, they also have the disadvantage of low molding processability. In addition, as a method to improve water resistance such as hygroscopicity or salt water resistance of polyamide resin,
53-80014, JP-A-56-167751, JP-A-56-109247, and JP-A-56-157451 disclose that polyamide resin contains ethylene as one component.
A method of blending a neutralized α,β-unsaturated monocarboxylic acid copolymer (ionomer resin) has been proposed. Although the compositions proposed in these prior art documents can improve water resistance such as water absorption and salt water decomposition resistance, they do not have the effect of improving impact resistance such as Izot impact strength, especially low-temperature impact resistance. It has the disadvantage of being inferior in some respects. Furthermore, as a method for improving the decrease in rigidity of the polyamide resin composition mentioned above, Japanese Patent Application Laid-Open No. 57-8246 discloses that crystalline polyolefin and low-crystalline ethylene.
A method of blending a graft modified composition with an α-olefin copolymer has been proposed. but,
In this method, it is difficult to control the melt fluidity of the modified polyolefin and the modified low-crystalline ethylene/α-olefin copolymer in the graft modified product due to crosslinking, and as a result, a polyamide composition with good dispersibility is obtained. The temperature range for improving impact resistance is significantly narrowed, and the improvement effect is small.Especially, the low-temperature isot impact strength and falling weight impact strength below -20°C are significantly reduced, and the melt fluidity of the composition is also reduced. There is a drawback that it does. Furthermore, in the prior art document, JP-A-55-
Publication No. 36279 describes the use of modified low-crystalline ethylene to improve the impact resistance of polyamide, as mentioned above.
When blending an α-olefin copolymer, if an unmodified low-crystalline ethylene/α-olefin copolymer is further blended, a polyamide composition with excellent appearance and color tone can be obtained. It is also described that the use ratio of the low-crystalline ethylene/α-olefin copolymer can be reduced, so that it has excellent economic effects. However, according to the description of the publication, especially the description of Examples and Comparative Examples, it is clear that the intrinsic viscosity [η] _B of the modified low-crystalline ethylene/α-olefin copolymer blended into polyamide and the modified group The ratio of the intrinsic viscosity [η] _C of the unmodified low-crystalline ethylene/α-olefin copolymer, which is the agent, and the value of [η] _B / [η] _C are both values close to 1, and the value is 0.9 or less. It won't happen. If we consider the effect of improving the impact resistance of the polyamide composition obtained at that time,
Compared to the experiment in which unmodified low-crystalline ethylene/α-olefin copolymer was blended alone (Comparative Example 1), impact resistance was improved, but modified low-crystalline ethylene/α-olefin copolymer Compared to the experiment (reference example) in which the modified low-crystalline ethylene/α-olefin copolymer was blended alone, the impact resistance was only improved in proportion to the blending ratio of the modified low-crystalline ethylene/α-olefin copolymer. Economic effects have only been achieved by reducing the amount of modified low-crystalline ethylene/α-olefin copolymer used. [ Regarding the effect of improving the impact resistance of the polyamide composition by blending it with polyamide in a proportion such that the ratio of [η] falls within a specific range,
A synergistic effect exists in the blending of the modified low-crystalline ethylene/α-olefin copolymer and the low-crystalline ethylene/α-olefin copolymer. The present invention was achieved by discovering that the effect is not limited to reducing the amount used. According to the present invention, the polyamide composition of the present invention has improved impact resistance such as isot impact strength and falling weight impact strength at low temperatures, stress resistance and resistance to water absorption and salt water decomposition under salt conditions. This composition has the characteristics of markedly improved water resistance, less decrease in rigidity, and excellent moldability due to less decrease in melt flowability. To summarize the present invention, the present invention comprises polyamide
(A), a modified low-crystalline ethylene/α-olefin copolymer (B), and a low-crystalline ethylene/α-olefin copolymer (C), the polyamide composition comprising: The composition of each component is 1 to 100 parts by weight of the modified low-crystalline ethylene/α-olefin copolymer (B) to 100 parts by weight of the polyamide (A).
1 to 100 parts by weight of the low crystalline ethylene/α-olefin copolymer (C).
[] The modified low-crystalline ethylene/α-olefin copolymer (B) is a base low-crystalline ethylene/α-olefin copolymer 100 containing ethylene component units as a main component. A product obtained by graft copolymerizing an unsaturated carboxylic acid or its derivative component unit in the range of 0.01 to 10 parts by weight, with a crystallinity of 40% or less, and in decalin at 135°C. Intrinsic viscosity [η] _B is 0.5 or
7 gl/g, [] The low crystalline ethylene/α-olefin copolymer (C) is composed mainly of ethylene component units, and its crystallinity is 40% or less. range, and the intrinsic viscosity [η] _C in decalin at 135°C is in the range of 0.5 to 7 dl/g, and [] the limit of the modified low-crystalline ethylene/α-olefin copolymer (B) The ratio of the viscosity [η] _B to the intrinsic viscosity [η] _C of the low-crystalline ethylene/α-olefin copolymer (C), [η] _B / [η] _C , is in the range of 0.24 to 0.62. The gist of the invention is a polyamide composition characterized by the following. The polyamide (A) used in the polyamide composition of the present invention is of sufficient molecular weight to produce molded articles, and is composed of a saturated organic dicarboxylic acid having 4 to 12 carbon atoms and a saturated organic dicarboxylic acid having 2 to 13 carbon atoms. It can be produced by condensing equimolar amounts of organic diamines having atoms. Here, if necessary, diamine can be used in the polyamide so that the amino group ends are in excess compared to the carboxyl group ends, or conversely, dicarboxylic acid can be used so that the carboxyl groups are in excess. can. These polyamides can also be produced from the amine and acid-forming derivatives and amine-forming derivatives, such as esters, acid chlorides, amine salts, and the like. Typical dicarboxylic acids used to make polyamides include adipic acid, pimelic acid, suberic acid, sebacic acid and dodecanedioic acid. On the other hand, typical diamines include hexamethylene diamine and octamethylene diamine. Furthermore, they can also be produced by self-condensation of polyamide lactams. Examples of polyamides include polyhexamethylene adipamide (6.6 nylon), polyhexamethylene azelamide (6.9 nylon), polyhexamethylene sebaamide (6.10 nylon) and polyhexamethylene dodecanoamide (6.12 nylon), There are polybis(4-aminocyclohexyl)methandodecanamides, or polyamides prepared by ring opening of lactams, namely polycaprolactam (6nylon), polylauritulactam or poly-11-aminoundecanoic acid. It is also possible to use polyamides produced by polymerization of at least two amines or acids used to produce the polyamides mentioned above, for example polymers made from adipic acid and isophthalic acid and hexamethylene diamine. be. It is also possible to use blends of polyamides such as nylon 6.6 and mixtures of nylon 6. The condensation polyamides used in the invention are preferably polyhexamethylene adipamide (nylon 6.6) or polyhexamethylene azeramide (nylon 6.9) and polycaprolactam (nylon 6). The modified low-crystalline ethylene/α-olefin copolymer (B) blended into the polyamide composition of the present invention is
Low-crystalline ethylene with ethylene as its main component.
Graft copolymerized with 0.01 to 10 parts by weight of unsaturated carboxylic acid or its derivative component units to 100 parts by weight of α-olefin copolymer,
Its crystallinity is in the range of 40% or less, and 135
It is necessary that the intrinsic viscosity [η] _B in decalin at ℃ is in the range of 0.5 to 7 dl/g, and in addition, the base material is a low-crystalline ethylene/α-olefin copolymer 100% of the weight of which the main component is ethylene. unsaturated carboxylic acid or its derivative component unit per part
Graft copolymerized in the range of 0.02 to 5 parts by weight, the crystallinity is in the range of 1 to 30%, and the intrinsic viscosity [η] _B in decalin at 135°C is in the range of 0.7 to 5 dl/g. It is preferable that the Furthermore, the modified low crystalline ethylene α-
Other physical properties of the olefin copolymer (B) include a molecular weight distribution (w/n) of usually 1.5 to 50, preferably 2.
to 30, and the glass transition temperature is usually -
It is in the range of 10°C or lower, preferably -20°C or lower.
If the grafting ratio of the unsaturated carboxylic acid or its derivative component unit in the modified low-crystalline ethylene/α-olefin copolymer is less than 0.01 part by weight, the compatibility with the polyamide is poor and the impact strength of the polyamide composition is reduced. However, if the amount exceeds 10 parts by weight, the degree of crosslinking of the graft modified product will increase, and even if it is blended into polyamide, the effect of improving the impact resistance of the composition will decrease. When the degree of crystallinity of the modified low-crystalline ethylene/α-olefin copolymer exceeds 40%, the impact strength of the polyamide composition decreases, and when the intrinsic viscosity thereof becomes lower than 0.5 dl/g, The impact strength of polyamide compositions decreased by 7 dl/g.
If it becomes larger, impact resistance and melt fluidity will decrease due to poor dispersion. The base polymer constituting the modified low-crystalline ethylene/α-olefin copolymer is a copolymer of ethylene and an α-olefin other than ethylene, and is a copolymer mainly composed of ethylene. It is a crystalline ethylene/α-olefin copolymer. Its ethylene content is usually in the range of 95 to 50 mol%, preferably 93 to 55 mol%, its crystallinity is usually in the range of 40% or less, preferably 30% or less, and its intrinsic viscosity [η] is usually 0.5 or
7 dl/g, preferably in the range of 0.7 to 5 dl/g, and its glass transition temperature is usually -10°C or lower, preferably -20°C or lower. The α-olefin component units other than ethylene constituting the low-crystalline ethylene/α-olefin copolymer include propylene, 1-butene, 1-bentene, 4-methyl-1-pentene, 1-hexene, 1- Examples include octene, 1-decene, and 1-dodecene. The unsaturated carboxylic acid or its derivative component unit of the graft monomer component constituting the modified low-crystalline ethylene/α-olefin copolymer (B) is as follows:
For example, acrylic acid, methacrylic acid, α-ethyl acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endocis-bicyclo[2.2.1]hept-5-ene-2, Unsaturated dicarboxylic acids such as 3-dicarboxylic acid (nadic acid), methyl-endocys-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (methyl nadic acid), acid halides of the unsaturated dicarboxylic acids , amides, imides, acid anhydrides, esters, and other unsaturated dicarboxylic acid derivatives, specifically, maleyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate,
Examples include dimethyl maleate and glycidyl maleate. Among these, unsaturated nacarboxylic acid or its acid anhydride is preferred, and maleic acid, nadic acid, or these acid anhydrides are particularly preferred. The graft monomer selected from the unsaturated carboxylic acid or its derivative is combined with low crystalline ethylene/α-
Various conventionally known methods can be employed to produce the modified low-crystalline ethylene/α-olefin copolymer by graft copolymerization with the olefin copolymer. For example, low crystalline ethylene α
- There is a method of melting the olefin copolymer and adding a graft monomer to carry out graft copolymerization, or a method of dissolving the olefin copolymer in a solvent and adding a graft monomer to carry out graft copolymerization. In any case, in order to efficiently graft copolymerize the graft monomer, it is preferable to carry out the reaction in the presence of a radical initiator. Grafting reactions are usually 60
It is carried out at a temperature between 350°C and 350°C. The proportion of the radical initiator used is usually in the range of 0.01 to 20 parts by weight per 100 parts by weight of the low-crystalline ethylene/α-olefin copolymer. Examples of the radical initiator include organic peroxides, organic peresters, and azo compounds. The low-crystalline ethylene/α-olefin copolymer (C) blended into the polyamide composition of the present invention has ethylene as its main component, and its crystallinity is low.
40% or less, and its intrinsic viscosity [η] _C in decalin at 135℃ is 0.5 to 7 dl/g
Furthermore, the degree of crystallinity must be within the range of 30% or less, and the temperature must be within the range of 135℃.
Intrinsic viscosity [η] _C in decalin is 0.7 to 5 dl/
Those in the range of g are preferable. Regarding other physical properties of the low-crystalline ethylene/α-olefin copolymer, the glass transition temperature is usually -10°C or lower;
Preferably it is in the range of -20°C or lower. The crystallinity of the low crystalline ethylene/α-olefin copolymer is
If it exceeds 40%, the effect of improving the impact resistance of the polyamide composition will decrease. In addition, 135 of the low crystalline ethylene/α-olefin copolymer
When the intrinsic viscosity in decalin at °C becomes less than 0.5 dl/g, the impact resistance of the polyamide composition decreases, and when it becomes greater than 7 dl/g,
The impact strength and melt viscosity of the polyamide composition will decrease. Here, the α-olefin component units other than ethylene include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene,
Examples include 1-dodecene. The low-crystalline ethylene/α-olefin copolymer is mainly composed of ethylene component units, and the content of the α-olefin component units constituting it is usually 5 to 50 mol%, preferably 7 to 45%. mole%
is within the range of Examples of the low-crystalline ethylene/α-olefin copolymer include ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene/4-methyl-1-pentene copolymer, and ethylene/1-hexene copolymer. Examples include polymers, ethylene/octene copolymers, ethylene/1-decene copolymers, and the like. In the polyamide composition of the present invention, when blending the modified low-crystalline ethylene/α-olefin copolymer (B) and the low-crystalline ethylene/α-olefin copolymer (C) with the polyamide, It is necessary to adjust the value of [η] _B / [η] _C , which is the ratio of the intrinsic viscosities [η] of both in decalin at 135°C, to a range of 0.24 to 0.62. If the ratio of the intrinsic viscosities of the two components is greater than 0.62, the impact resistance of the polyamide composition will decrease, and if it is less than 0.24, the impact strength will also decrease. In the polyamide composition of the present invention, the blending ratio of the modified low-crystalline ethylene/α-olefin copolymer (B) to 100 parts by weight of the polyamide (A) must be in the range of 1 to 100 parts by weight. The amount is more preferably 5 to 80 parts by weight, particularly preferably 5 to 50 parts by weight. When the blending ratio of the modified low-crystalline ethylene/α-olefin copolymer exceeds 100 parts by weight, the rigidity and melt fluidity of the polyamide composition decrease, and when it becomes less than 1 part by weight, the polyamide composition deteriorates. The impact resistance, stress crack resistance and water resistance of the product will decrease. Further, the blending ratio of the low crystalline ethylene/α-olefin copolymer (C) to 100 parts by weight of the polyamide (A) needs to be in the range of 1 to 100 parts by weight,
Further, 5 to 80 parts by weight, particularly preferably 5
and 50 parts by weight. The blending ratio of the low crystalline ethylene/α-olefin copolymer is 100
If the amount is more than 1 part by weight, the rigidity and melt flowability of the polyamide composition will be reduced, and if it is less than 1 part by weight, the impact resistance, stress crack resistance and water resistance of the polyamide composition will be reduced. Become. Furthermore, in the polyamide composition of the present invention, the blending ratio of the low crystalline ethylene/α-olefin copolymer (C) to 100 parts by weight of the modified low-crystalline ethylene/α-olefin copolymer (B) is usually It ranges from 5 to 2000 parts by weight, preferably from 10 to 1500 parts by weight. Furthermore, in the polyamide composition of the present invention, the graft copolymerized unsaturation is based on the total amount of the modified low-crystalline ethylene/α-olefin copolymer (B) and the ethylene/α-olefin copolymer (C). The proportion of carboxylic acid or its derivative component units is usually 0.02 to 7.
% by weight, preferably in the range 0.05 to 5% by weight. In addition to the above-mentioned three essential components, the polyamide composition of the present invention may optionally contain antioxidants, ultraviolet absorbers, photoprotectants, phosphite stabilizers, peroxide decomposers, basic adjuvants, Contains fillers such as nucleating agents, plasticizers, lubricants, antistatic agents, flame retardants, pigments, dyes, carbon black, asbestos, glass fibers, potassium titanate whiskers, mica, carrion, talc, silica, and silica alumina. It is also possible to do so. Furthermore, other polymers can be blended into the composition of the present invention within a range that does not impair its physical properties. The blending ratio of these additives is within an appropriate range. The polyamide compositions of the present invention are prepared by melt mixing in a variety of ways. For example, two essential components may be premixed and then mixed with the remaining components, or three essential components may be mixed with other remaining components at the same time. Moreover, the above-mentioned additives, such as antioxidants, can be added at any of these stages as necessary. The polyamide composition of the present invention has excellent properties such as rigidity, impact resistance, and water resistance. Among them, the composition obtained by melt-mixing the polyamide (A) component into a premix prepared by melt-mixing the components (B) and (C) in particular has particularly good performance. is excellent. The melt fluidity [melt flow rate (MFR, 235°C, 1000g load)] of the composition of the present invention is usually
0.1 to 500g/10min, preferably 0.2 to 500g/10min
The range is 100g/10min. The polyamide composition of the present invention can be molded into various shapes by various conventionally known melt molding methods. Examples include methods such as injection molding, extrusion molding, compression molding, and foam molding, and are used for a wide range of applications including automobile parts, electrical appliances, and electrical parts. Next, the present invention will be specifically explained using examples. In addition, in the Examples and Comparative Examples, the degree of crystallinity and the intrinsic viscosity [η] were determined by the following method. Crystallinity: Determined by x-ray diffraction at 23°C. Intrinsic viscosity [η]: Determined in decalin at 135°C. Example 1 Maleic anhydride grafted ethylene/propylene copolymer [ethylene content 80 mol%, [η]
1.53 dl/g, density 0.86 g/cm ³ , crystallinity 14%] and ethylene-propylene copolymer [ethylene 80 mol%, [η] 2.53 dl/g, density 0.86 g/cm ³ , crystallinity
15%] were premixed in a 30 mmφ extruder (L/D=28, 230°C) to the proportions shown in Table 1. Next, this premix and nylon 6 [manufactured by Toray Industries, Asilan 1021×F, MFR 3.74 g/10 min, Q conditions] were mixed in the proportions shown in Table 1 to form a dry blend consisting of two types of pellets. Prepared. Furthermore, a single screw extruder (L/D=28,
30 mmφ) to prepare a melt blend (pellet shape). The pellets were vacuum-dried at 100° C. for one day and night, and then injection molded under the following conditions to prepare specimen for measuring physical properties. Cylinder temperature: 260°C Injection pressure: 650Kg/cm ² Injection time: 10sec Mold temperature: 80°C Subsequently, physical properties were evaluated using the following method. MFR measurement: ASTM D-1238-79 Q conditions
MFR was measured. Bending test: Using a 1/8″ thick test piece, bending modulus FM according to ASTM D-790-80
(Kg/cm ² ) and bending yield strength FS (Kg/cm ² ) were measured. The test piece was conditioned at 23℃ and 50%
The test was carried out for 3 days in a constant temperature and humidity room at RH. Falling weight impact strength: A weight of a certain shape is dropped from a height of 90cm onto a test piece (diameter 50mmφ, thickness 1.2mm) placed horizontally at -60℃, and by varying the weight of the weight, 50 of test pieces
The falling weight impact strength was evaluated based on the weight (g) of the weight required for % to break. The test pieces were conditioned for 3 days in a constant temperature and humidity room at 23°C and 50% RH. Izot impact strength: 23°C and -40°C according to ASTM D256 using 1/8" thick test piece
Notched Izo impact strength was measured.
Conditioning of the test piece was carried out for 3 days in a constant temperature and humidity room at 23°C and 50% RH. Water absorption test: According to ASTM D570, test specimens (2 inch diameter, 1/8 inch thickness) were heated at 100℃ for 24 hours.
After drying for an hour, a water absorption test was conducted in water at 50°C for 48 hours, and the water absorption rate (%) was determined from the weight change rate of the test piece. The results are shown in Table 1. Examples 1 to 11, Comparative Examples 1 to 5 Modified low crystalline ethylene/α-olefin copolymer (B) and low crystalline ethylene/α-olefin copolymer shown in Table 1
A blend was prepared in the same manner as in Example 1, except that the olefin copolymer (C) was used in the proportions shown in Table 1, and its physical properties were measured. The results are shown in Table 1.
Table 1 also shows the physical properties of the polyamide when the modified low-crystalline ethylene/α-olefin copolymer (B) and the low-crystalline ethylene/α-olefin copolymer (C) were not blended. Comparative example 1).

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Claims (1)

[Claims] 1. Polyamide (A), modified low crystalline ethylene α-
Olefin copolymer (B) and low crystalline ethylene
A polyamide composition containing an α-olefin copolymer (C), wherein the composition of each component in the composition is such that the modified low-crystalline ethylene/α - 1 or more olefin copolymer (B)
100 parts by weight of the modified low-crystalline ethylene/α-olefin copolymer (C), and 1 to 100 parts by weight of the modified low-crystalline ethylene/α-olefin copolymer (C); (B) contains an unsaturated carboxylic acid or its derivative component unit in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the base low-crystalline ethylene/α-olefin copolymer mainly composed of ethylene component units. It is obtained by graft copolymerization, the crystallinity is in the range of 40% or less, and the intrinsic viscosity [η] _B in decalin at 135°C is 0.5 or less.
7d1/g, and [] The low-crystalline ethylene/α-olefin copolymer (C) is mainly composed of ethylene component units, and its crystallinity is 40% or less. and the intrinsic viscosity [η] _C in decalin at 135°C is in the range of 0.5 to 7d1/g, and [] the modified low-crystalline ethylene/α-olefin copolymer (B) The ratio of the intrinsic viscosity [η] _B of the low-crystalline ethylene/α-olefin copolymer (C) to the intrinsic viscosity [η] _C of the low-crystalline ethylene/α-olefin copolymer (C), [η] _B /[η] _C has a value of 0.24 to 0.62. A polyamide composition comprising: