JP3345141B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition obtained by blending a specific thermoplastic graft polymer with a specific low-hardness thermoplastic polyurethane. Since the resin composition of the present invention is excellent in moldability (releasing property, low molding distortion), it is useful as various molding materials.

[0002]

2. Description of the Related Art Thermoplastic polyurethane (hereinafter referred to as T
PU) has a high modulus of elasticity, excellent strength, abrasion resistance, chemical resistance, bending resistance and oil resistance, and has many features such as the ability to apply ordinary plastic molding methods. Are increasingly used in a wide range of applications as alternatives to rubber and plastics.

[0003] However, since TPU has a higher tackiness than other thermoplastic resins, it has a drawback that it is poor in injection moldability such as poor mold separation in injection molding and easy adhesion of molded products. . Furthermore, in TPU,
Since the molding shrinkage in the injection molding greatly changes depending on various conditions such as molding conditions and mold shapes, there is a disadvantage that it is not easy to obtain a molded product with high accuracy. As a method of improving the releasability, there is a method of adding a lubricant to the TPU to prevent tackiness. However, in a molded product, a problem of poor appearance and poor adhesion to other resins due to bleed out of the lubricant occurs. Often. There is also a method of applying a release agent to the surface of a mold during injection molding. However, this method may cause a defective surface of a molded product and has poor workability.

[0004] It is an object of the present invention to provide a soft resin composition which exhibits excellent mold releasability even when a lubricant is not blended, can be molded with good workability, and has less molding distortion. .

[0005]

According to the present invention, the object is to provide (A) a molecular weight of 3500 comprising a diol unit containing at least 50 mol% of a 3-methyl-1,5-pentanediol unit and a dicarboxylic acid unit. The polyester diol, the organic diisocyanate, and the chain extender having a ratio of isocyanate group equivalent number / hydroxyl equivalent number of 0.98 to 10,000 are used.
A thermoplastic polyurethane having a nitrogen atom content of 1.9% by weight or less obtained by reacting at a ratio of 1.08, and (B) an elastomer obtained by graft polymerization of an aromatic vinyl compound and a vinyl cyanide compound. The obtained thermoplastic graft polymer is converted into the thermoplastic polyurethane (A) /
The weight ratio of the thermoplastic graft polymer (B) is 20/8
This is achieved by providing a resin composition characterized by being contained at a ratio of 0 to 90/10.

The polyester diol constituting the thermoplastic polyurethane (A) which is one component of the resin composition of the present invention is 3-methyl-1,5-pentanediol (MP
D) unit _{[-O-CH 2 CH 2 -CH} (CH 3) -CH 2 CH
It is important that the content of ( _2- O-) be at least 50 mol% based on the total diol unit, and the molecular weight (number average molecular weight) be in the range of 3500 to 10000. Generally, a molecular weight of 350
Since a polyester diol of 0 or more has high crystallinity, a polyurethane obtained from the polyester diol cannot secure flexibility, and tends to have poor cold resistance and elastic recovery. By including 50 mol% or more of MPD units based on all diol units in the molecule of the polyester diol used,
It is possible to obtain a polyurethane in which these disadvantages have been eliminated, and thereby it is possible to obtain a flexible resin composition. The resulting polyurethane, and thus the resin composition,
In order to provide better cold resistance and flexibility, the content of MPD units based on all diol units is preferably 70 mol% or more. On the other hand, if it is 50 mol% or less, preferably 30 mol% or less based on all diol units, it may have a diol unit other than the MPD unit. Examples of the diol unit other than the MPD unit include ethylene glycol, 1,4-butanediol,
Structural units which can be derived from glycols other than MPD, such as -methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, and 1,6-hexanediol. Examples of the dicarboxylic acid unit constituting the polyester diol include structural units that can be derived from an aliphatic dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, and sebacic acid. Of these, the adipic acid unit is preferable. If the molecular weight of the polyester diol is less than 3500, it is difficult to produce a low-hardness polyurethane having a JIS-A hardness of 65 or less, and the obtained polyurethane has poor physical properties. Properties are not sufficient, for example, is not exhibited. On the other hand, when the molecular weight of the polyester diol exceeds 10,000,
Not only does the productivity of the polyurethane decrease, but also the melt viscosity of the obtained polyurethane increases, and it becomes difficult to stably mold the resin composition using the same. From these viewpoints, the molecular weight of the polyester diol is more preferably in the range of 4000 to 7000.

[0007] The method for producing the polyester diol is not particularly limited. For example, a polyester diol can be produced by using a diol such as MPD, a carboxylic acid, or an ester thereof as a raw material compound and performing an esterification or transesterification reaction according to a known production method.

The organic diisocyanate used in the present invention includes, for example, 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate,
Molecular weight of 50 such as 1,5-naphthylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate
A diisocyanate of 0 or less is preferred, and among these, 4,4'-diphenylmethane diisocyanate is particularly preferred. Examples of the chain extender include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-
It is preferable to use a diol having a molecular weight of 400 or less, such as bis (β-hydroxyethoxy) benzene, and among them, it is particularly preferable to use 1,4-butanediol.

In the present invention, the thermoplastic polyurethane (A) comprises the polyester diol, the organic diisocyanate and the chain extender in a ratio of isocyanate group equivalent number / hydroxyl equivalent number of 0.98 to 1.08. It is obtained by reacting at a certain ratio. If the ratio of the number of isocyanate groups / the number of hydroxyl groups is less than 0.98, the properties of the obtained polyurethane and, in turn, the resin composition are greatly reduced. on the other hand,
If the ratio exceeds 1.08, the stability of the resin composition when stored in the form of pellets or the like is poor, and partial crosslinking occurs between polyurethane molecular chains during storage, thus causing problems such as poor molding. Happens. As for the method for producing the thermoplastic polyurethane (A) by polymerizing the polyester diol, the organic diisocyanate and the chain extender, a known urethane-forming reaction technique can be employed. Among them, it is preferable to carry out melt polymerization substantially in the absence of a solvent,
Particularly, a continuous melt polymerization method using a multi-screw extruder is preferable. Polyurethane obtained by continuous melt polymerization is 8
It is generally superior in strength as compared with polyurethane obtained by solid-state polymerization at 0 to 130 ° C. The melt polymerization temperature is not particularly limited, but is preferably in the range of 180 to 260 ° C.
In particular, when melt polymerization is performed with the upper limit temperature kept at 240 ° C. or lower, a high-quality polyurethane excellent in heat resistance and moldability can be obtained.

The thermoplastic polyurethane (A) used in the present invention has a nitrogen atom content of 1.9% by weight or less.
For polyurethanes exceeding 1.9% by weight, JIS-A
Since the hardness does not have a low hardness of about 65 or less, the hardness of the obtained resin composition increases, and the inherent characteristics of the elastomer are impaired. The nitrogen atom content is preferably in the range of 1.4 to 1.9% by weight from the viewpoint of obtaining a thermoplastic polyurethane having low hardness and excellent productivity.

[0011] In the resin composition of the present invention, together with the above-mentioned thermoplastic polyurethane (A),
It is also an important requirement that a thermoplastic graft polymer (B) obtained by graft-polymerizing a graft monomer composed of an aromatic vinyl compound and a vinyl cyanide compound onto a graft substrate composed of an elastomer in a specific relative ratio is used. In the present invention, the thermoplastic polyurethane (A) /
The weight ratio of the thermoplastic graft polymer (B) is 20/80.
９０90/10. The blending ratio of the thermoplastic graft polymer (B) is 9% of the thermoplastic polyurethane (A).
When the amount is less than 10 parts by weight with respect to 0 parts by weight, the effect of the present invention is hardly exhibited. In addition, the blending ratio of the thermoplastic graft polymer (B) is the thermoplastic polyurethane (A).
When the amount exceeds 80 parts by weight with respect to 20 parts by weight, the hardness of the obtained resin composition is increased, and the inherent characteristics of the elastomer are impaired.

As the above-mentioned elastomer to be a graft base, one having a secondary transition temperature lower than -30 ° C. is preferred. Further, as the aromatic vinyl compound which is one of the graft monomers, for example, styrene, α-methylstyrene, alkyl-substituted styrene, halogen-substituted styrene and the like are used, and styrene is particularly preferable. Further, as the vinyl cyanide compound, for example, acrylonitrile, methacrylonitrile and the like are used,
In particular, it is preferable to use acrylonitrile.

As the thermoplastic graft polymer used in the present invention, for example, a copolymer obtained by adding both acrylonitrile and styrene graft monomers to a latex of a butadiene polymer and emulsion-polymerizing the same (hereinafter referred to as ABS resin) ).
As the butadiene-based polymer latex, polybutadiene latex, acrylonitrile-butadiene copolymer latex, styrene-butadiene copolymer latex, and the like are used. The proportion of each of the above components in the ABS resin is 5 to 50% by weight of butadiene and 20 to 50% of styrene.
85% by weight, acrylonitrile 5 to 40% by weight.
Further, as another example of the thermoplastic graft polymer used in the present invention, a resin obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto an ethylene-propylene rubber (hereinafter, abbreviated as AES resin). Do). As the ethylene-propylene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, or the like is used. The weight ratio of ethylene to propylene is preferably in the range of 9: 1 to 2: 8. Examples of the diene monomer include norbornenes such as alkenyl norbornene, cyclic dienes such as dicyclopentadiene, and aliphatic dienes such as hexadiene. The diene monomers are used alone or in combination of two or more. The weight ratio of the ethylene-propylene rubber to the graft monomer such as an aromatic vinyl compound and a vinyl cyanide compound is from 5:95 to 5: 5.
The range of 0:50 is appropriate, and 10:90 to 40:60.
Is preferable. The AES resin is produced by a bulk polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk-suspension polymerization method, or the like.

The resin composition of the present invention can be produced by mixing the above-mentioned thermoplastic polyurethane (A) and thermoplastic graft polymer (B) by a desired method. For example, the thermoplastic polyurethane (A) and the thermoplastic graft polymer (B) are preliminarily mixed at a predetermined ratio using a vertical or horizontal mixer, which is usually used for mixing resin materials, and then mixed. Screw or twin screw extruder,
Using a mixing roll, Banbury mixer, etc.
The resin composition of the present invention is produced by heating and kneading in a batch system or a continuous system. In addition, at the time of mixing, in order to improve the light resistance, heat resistance and the like, stabilizers, plasticizers, lubricating agents such as montanic acid wax, fatty acid amide, fillers, antistatic agents, additives such as pigments, the effect of the present invention Can be added in such an amount that does not impair.

[0015]

The present invention will be described below with reference to examples. In the following Examples and Comparative Examples, an injection molding machine (FN manufactured by Nissei Plastics Industries, Ltd.) was used by using the obtained resin or resin composition.
S80S12ASE, cylinder temperature 170-200
° C, nozzle temperature 200 ° C, mold temperature 30 ° C, injection pressure 5
0-80 kgG / cm ² ), a disc-shaped material (diameter 12
(0 mm, thickness 2 mm), and injection moldability and physical properties of a molded article were evaluated from the following viewpoints.

(Hardness) The obtained molded product (disc-like material)
The sheets were stacked and measured by a hardness meter (JIS-A).

(Releasability from Mold) Table 1 shows the degree of difficulty in removing a molded product from the mold during injection molding.
It was determined based on the following criteria.

[0018]

[Table 1]

(Molding strain) The molding strain represents the degree of deformation of a molded product with respect to a mold, and was determined by the following equation.

[0020]

(Equation 1)

Reference Example 1 (Production of Polyester Diol PMPA6000)
2643 g of methyl-1,5-pentanediol and 2920 g of adipic acid were charged into a reactor, and 200
The esterification reaction was carried out while distilling the water generated at ° C out of the system. When the acid value of the reaction product became 30 or less, 80 mg of tetraisopropyl titanate was added, and 200 to 1
The reaction was continued while reducing the pressure to 00 mmHg. Acid value is 1.
When the value reached 0, the degree of vacuum was gradually increased by a vacuum pump to complete the reaction. As a result, 3-methyl-1,5-
4650 g of a polyesterdiol having a number average molecular weight of 6000 composed of pentanediol units and adipic acid units (hereinafter abbreviated as PMPA6000) was obtained.

Reference Example 2 (Production of Polyester Diol PMPA4000)
A reactor was charged with 2,714 g of methyl-1,5-pentanediol and 2,920 g of adipic acid, and an esterification reaction was carried out in the same manner as in Reference Example 1. As a result, 3-methyl-
4,700 g of a polyester diol having a number average molecular weight of 4000 composed of 1,5-pentanediol units and adipic acid units (hereinafter abbreviated as PMPA4000)
Obtained.

Reference Example 3 (Production of Polyester Diol PMBA6000)
2520 g of a mixture of methyl-1,5-pentanediol and 1,4-butanediol (molar ratio 80:20) and 2,920 g of adipic acid were charged into a reactor, and an esterification reaction was carried out in the same manner as in Reference Example 1. As a result, 3-methyl-
1,5-pentanediol unit, 1,4-butanediol unit (3-methyl-1,5-pentanediol unit:
4450 g of a polyesterdiol having a number average molecular weight of 6000 (hereinafter abbreviated as PMBA 6000) comprising 1,4-butanediol units (molar ratio = 80: 20) and adipic acid units was obtained.

Example 1 A mixture of the polyester diol (PMPA6000) obtained in Reference Example 1 and 1,4-butanediol (hereinafter abbreviated as BD) in a molar ratio of 1: 2.48 was used as a mixture. Heat to 50 ° C
4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), which was heated and melted, was mixed with polyesterdiol: MDI: BD at a molar ratio of 1: 3.48.
At a ratio of 2.48, the mixture was continuously charged into a twin-screw extruder rotating in the same direction by a metering pump to perform a continuous melt polymerization reaction. When the interior of the twin screw extruder is divided into three zones of a front part, an intermediate part and a rear part, the temperature (polymerization temperature) of the intermediate part which becomes the highest is 2
30 ° C. The resulting thermoplastic polyurethane was continuously extruded into water in the form of a strand, and then formed into pellets with a pelletizer. The obtained thermoplastic polyurethane pellets and ABS resin (Nippon Synthetic Rubber, ABS1
2) was supplied to a 25 mmφ extruder (cylinder temperature 200 ° C., die temperature 180 ° C.) at a weight ratio of 75 to 25, and was melt-kneaded there to obtain resin composition pellets. Using the obtained resin composition, injection moldability and physical properties of molded articles were evaluated. The evaluation results are shown in Table 2 below.

Examples 2 and 3, Comparative Example 1 A resin composition was prepared and injection-molded in the same manner as in Example 1 except that the mixing ratio between the thermoplastic polyurethane and the ABS resin was changed. Table 2 below shows the injection moldability of the obtained resin composition and the evaluation results of physical properties of the obtained molded article.

Comparative Example 2 The thermoplastic polyurethane alone obtained in Example 1 was subjected to the same injection molding as in Example 1. Table 2 below shows the evaluation results of the injection moldability and the physical properties of the molded product.

Comparative Example 3 An ABS resin (ABS12, manufactured by Nippon Synthetic Rubber) alone was subjected to the same injection molding as in Example 1. Table 2 below shows the evaluation results of the injection moldability and the physical properties of the molded product.

Comparative Example 4 AES resin (manufactured by Nippon Synthetic Rubber, AES110) alone was subjected to the same injection molding as in Example 1. Table 2 below shows the evaluation results of the injection moldability and the physical properties of the molded product.

Example 4 Instead of the polyester diol of Reference Example 1, the polyester diol of Reference Example 2 (PM
PA4000) and the polyester diol, MDI and BD were charged in the molar ratios shown in Table 3 in Example 1.
By performing the reaction and pelletizing in the same manner as
A thermoplastic polyurethane pellet was obtained. In the same manner as in Example 2, the thermoplastic polyurethane was treated with ABS.
A resin (made by Nippon Synthetic Rubber, ABS12) was kneaded and added to produce a pellet of the resin composition, which was used to perform injection molding to produce a molded product. The results of evaluation of the injection moldability of the obtained resin composition and the physical properties of the obtained molded product are shown in Table 3 below.
Shown in

[Example 5] AES instead of ABS resin
Pellets of the resin composition were produced in the same manner as in Example 4 except that a resin (manufactured by Nippon Synthetic Rubber, AES110) was used, and injection molding was performed using the pellets to produce a molded article. Table 3 below shows the injection moldability of the obtained resin composition and the evaluation results of the physical properties of the obtained molded product.

Comparative Example 5 The thermoplastic polyurethane obtained in Example 4 alone was subjected to the same injection molding as in Example 1. Table 3 below shows the results of the evaluation of the injection moldability and the physical properties of the molded product.

Example 6 Instead of the polyester diol of Reference Example 1, the polyester diol of Reference Example 3 (PM
BA6000) and the polyester diol, MDI and BD were charged at the molar ratios shown in Table 3.
By performing the reaction and pelletizing in the same manner as
A thermoplastic polyurethane pellet was obtained. In the same manner as in Example 2, the thermoplastic polyurethane was treated with ABS.
A resin (made by Nippon Synthetic Rubber, ABS12) was kneaded and added to produce a pellet of the resin composition, which was used to perform injection molding to produce a molded product. The results of evaluation of the injection moldability of the obtained resin composition and the physical properties of the obtained molded product are shown in Table 3 below.
Shown in

[Example 7] AES instead of ABS resin
Pellets of a resin composition were produced in the same manner as in Example 6 except that a resin (manufactured by Nippon Synthetic Rubber, AES110) was used, and injection molding was performed using the pellets to produce a molded article. Table 3 below shows the injection moldability of the obtained resin composition and the evaluation results of the physical properties of the obtained molded product.

Comparative Example 6 The thermoplastic polyurethane obtained in Example 6 alone was subjected to the same injection molding as in Example 1. Table 3 below shows the results of the evaluation of the injection moldability and the physical properties of the molded product.

[0035]

[Table 2]

[0036]

[Table 3]

From the results shown in Tables 2 and 3, Example 1
When the resin compositions of the present invention are subjected to injection molding,
It can be seen that the releasability from the mold is good, and a soft molded product with little molding distortion is provided. On the other hand, in the case of the thermoplastic polyurethane alone (Comparative Examples 2, 5 and 6) and in the case of the resin composition in which the thermoplastic polyurethane is too large beyond the range in the present invention (Comparative Example 1), the adhesion to the mold is low. It is clear that the moldability is inferior because the molding strain is remarkable and the molding distortion is large. In the case of using only the thermoplastic graft polymer (Comparative Examples 3 and 4), the hardness of the obtained molded product was high,
It turns out that it does not have the characteristic as an elastomer.

[0038]

According to the present invention, there is provided a resin composition which is excellent in both properties of an elastomer and moldability (releasability, low molding distortion).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 75/04-75/12 C08L 55/00-55/04

Claims (1)

(57) [Claims] 1. A polyester diol having a molecular weight of 3500 to 10000 comprising a diol unit containing 50 mol% or more of 3-methyl-1,5-pentanediol unit and a dicarboxylic acid unit, an organic diisocyanate, and a chain extender. And the ratio of isocyanate group equivalents / hydroxyl equivalents is 0.1.
A thermoplastic polyurethane having a nitrogen atom content of 1.9% by weight or less obtained by reacting at a ratio of 98 to 1.08;
And (B) a thermoplastic graft polymer obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto the elastomer, wherein the thermoplastic polyurethane (A) / the thermoplastic graft polymer (B) has a weight ratio of 20 / A resin composition, which is contained at a ratio of 80 to 90/10.