JP4414577B2 - Method for producing polymer whisker composite - Google Patents

Description

【００２６】
１）Synd.Pst：シンジオタクティックポリスチレン
PMPIA：ポリ（ｍ−フェニレンイソフタルアミド）
２）p-AcOBA：ｐ−アセトキシ安息香酸
p-AcABA：ｐ−アセトアミノ安息香酸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polymer whisker composite in which a polymer whisker is directly polymerized by solid phase polymerization in an amorphous part of a crystalline polymer, and the polymer whisker is finely dispersed in the amorphous part of the crystalline polymer. The present invention relates to a method for manufacturing a body.
[0002]
[Prior art]
In recent years, the development of ultra-high performance materials by compounding has come to be demanded, and polymer whiskers as reinforcing materials have attracted attention. Whisker is generally a short fiber with an aspect ratio (axial ratio) of 10 or more, and unlike high-elasticity and high-strength fibers (graphite, aramid, etc.) that exhibit only a one-dimensional reinforcing effect, by adjusting its aspect ratio It can be formed into uniform short fibers having a length of 100 μm and a thickness of 5 μm or less, so that the material to be reinforced can be reinforced two-dimensionally and isotropically. In addition, whisker has an advantage that it can be repeatedly used by recycling because it maintains its effect as a reinforcing agent even after remelting and molding, unlike the fiber reinforcing material. Further, the polymer whisker has a light specific gravity compared to conventional inorganic whiskers such as barium titanate, and can exhibit high specific strength. Conventionally, for example, polyoxymethylene, specific epoxy, polyester, and polyurethane resin have been known as polymer whiskers, but these have a low melting point, and the reinforcing material has a problem in heat resistance. On the other hand, poly-p-oxybenzoyl having a rigid aromatic ring, poly (2-oxy-6-naphthoyl), poly-p-mercaptobenzoyl, aromatic polyimide, and the like are disclosed as heat resistant high melting point whiskers. . As a method for producing these polymer whiskers, for example, polyoxymethylene is obtained by cationic polymerization of trioxane under dilute conditions, poly-p-oxybenzoyl, poly (2-oxy-6-naphthoyl), poly-p- Mercaptobenzoyl and the like are obtained by precipitating and isolating corresponding monomers as whisker crystals from a solution by high-temperature solution polymerization in a high-boiling paraffinic solvent under dilute conditions. No. 61-276819 and JP-A 61-285217. The aromatic polyimide whisker is produced by crystallizing the monomer in the crystalline state after whisker crystallization of the monomer. Thus, in the prior art, a method of polymerizing and isolating the whisker-forming monomer in a dilute condition or in a special form after molding is taken, and its low productivity and difficulty in reinforcing the material after isolation are taken. There was a problem of dispersibility. In particular, it has been pointed out that the difficult dispersibility of whiskers not only complicates the compounding process but also causes whisker defects.
[0003]
On the other hand, JP-A-8-90677 discloses a polymer whisker composite obtained by melt-kneading a whisker-forming monomer in a thermoplastic resin as a material to be reinforced and directly polymerizing at 250 to 350 ° C. A manufacturing method is disclosed. This method has an advantage that processes such as whisker polymerization and isolation, and redispersion into a resin can be greatly simplified. However, in this method, an amorphous resin is used as the thermoplastic resin, and the resin is produced under severe conditions such as polymerization at a high temperature of 300 ° C. or higher for a long time (3 hours or longer). In this method, there is a problem that even if the thermoplastic resin that is a corner reinforcement material is reinforced with whiskers, the thermoplastic resin itself is deteriorated by heat. Furthermore, since the polymerization of the whisker-forming monomer proceeds in the molten state of the thermoplastic resin, the polymer whisker is finely dispersed throughout the thermoplastic resin, and if a crystalline polymer is used as the thermoplastic resin, Since deterioration of the polymer (modification of the primary structure of the polymer) occurs, the structure of the crystal part is adversely affected, so that there is a problem that the performance of the polymer itself, which is a material to be reinforced, is deteriorated. In this method, it is difficult to reinforce only the amorphous part of the crystalline polymer.
[0004]
[Problems to be solved by the invention]
The object of the present invention is not only to simplify the manufacturing process of polymer whiskers and the process of compounding to a to-be-reinforced material, but also to prevent the thermal deterioration of the crystalline polymer while increasing the strength of the polymer whisker composite It is in providing the manufacturing method of.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems and strengthen the crystalline thermoplastic polymer Y, the present inventors use polymer whiskers, which are dispersed in the amorphous part of Y, and the amorphous part of Y is dispersed. Considered strengthening. As a result, the monomer Xm capable of forming the polymer whisker X is almost uniformly mixed and blended in the crystalline thermoplastic polymer Y, and the Xm is dissolved in the amorphous portion of the matrix composed of Y, and then covered. When solid phase polymerization of Xm is performed at a low temperature below the melting point of the reinforced polymer Y, the polymerization of Xm proceeds in the amorphous part, and the polymer whisker is finely dispersed and strengthened in the amorphous part by growing to X. , Y has been found to obtain a polymer whisker composite that significantly suppresses thermal degradation of Y, and has led to the completion of the present invention.
[0006]
That is, the present invention mixes a monomer capable of forming a polymer whisker with a crystalline polymer, and then heats the mixture to a temperature not higher than the melting point of the crystalline polymer. A method for producing a polymer whisker composite in which a polymer whisker is finely dispersed in an amorphous part of a crystalline polymer, wherein the monomer dissolved in the part is solid-phase polymerized to form a polymer whisker .
[0007]
In the present invention, the monomer (Xm) capable of forming the polymer whisker is p-acetoxybenzoic acid, 2-acetoxy-6-naphthalenedicarboxylic acid, p-acetaminobenzoic acid, p-acetoxy-mercaptobenzoic acid, p -Oxybenzoyl chloride, 2-oxy-6-naphthoyl chloride, phenyl (p-oxybenzoate), phenyl (2-oxy-6-naphthoate), p-aminobenzoic acid chloride, p-mercaptobenzoyl chloride. It is a manufacturing method of the characteristic polymer whisker composite.
[0008]
In the present invention, the crystalline polymer is a polyolefin or an aromatic polyamide, and monomers capable of forming a polymer whisker are p-acetoxybenzoic acid, 2-acetoxy-6-naphthalenedicarboxylic acid, p-acetaminobenzoic acid, p-acetoxy-mercaptobenzoic acid, p-oxybenzoyl chloride, 2-oxy-6-naphthoyl chloride, phenyl (p-oxybenzoate), phenyl (2-oxy-6-naphthoate), p-aminobenzoic acid chloride, A method for producing a polymer whisker complex, which is p-mercaptobenzoyl chloride .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the method of the present invention will be described in detail.
The polymer whisker X used in the present invention is a short fiber-like polymer crystal having a diameter of 1 nm to 10 μm and a length of 0.2 μm to 1 mm. This is similar to whiskers obtained from metals, graphites, oxides, carbides, nitrides, etc., commonly known as inorganic whiskers, and is a so-called stretched chain in which a crystal composed of polymer chains is grown in a uniaxial direction. It has a structure and contains almost no crystal defects. That the obtained polymer crystal is a whisker can be confirmed by an electron microscope, X-ray diffraction or the like.
[0010]
Further, the polymer whisker X in the present invention is preferably a rigid polymer because it is required to significantly improve the strength as a composite reinforcing material. That is, it is desirable to have a structure in which the bond forming the polymer chain is strong, the occupation cross-sectional area of the molecular chain is small, and the chain elongation is small. When the physical conditions reflected from these structures are expressed quantitatively, the theoretical crystal elastic modulus is 150 Gpa or higher and the theoretical strength is 2.0 Gpa or higher, or the tensile elastic modulus is 100 Gpa or higher and the tensile strength is 2. It is considered to be a material having mechanical properties of 0 Gpa or more. Materials satisfying this condition are poly (p-oxybenzoyl), poly (2-oxy-6-naphthoyl), poly (p-benzamide), poly (p-mercaptobenzoyl), poly (p-phenylene terephthalamide). , Polyazomethine, poly (p-phenylenepyromellitimide), polybenzobisoxazole, polybenzobisthiazole, polybenzoxazole and the like. Among them, as a material used in the present invention, as a polymer whisker formed using a monomer Xm capable of forming a polymer whisker as a starting material, p-acetoxybenzoic acid is used as an aromatic hydroxycarboxylic acid. Poly (p-oxybenzoyl) formed, poly (2-oxy-6-naphthoyl) formed using 2-acetoxy-6-naphthalenedicarboxylic acid, p-acetaminobenzoic acid used as aromatic aminocarboxylic acids Poly (p-benzamide) formed in this manner and poly (p-mercaptobenzoyl) formed using p-acetoxy-mercaptobenzoic acid as the aromatic mercaptocarboxylic acid are preferred. These monomers Xm are suitable because they can be uniformly blended with a crystalline thermoplastic polymer serving as a composite matrix, and the polymerization conditions are a condensation reaction only by heating. As the starting monomer Xm for these polymer whiskers, in addition to the above, for example, when X is poly (p-oxybenzoyl) or poly (2-oxy-6-naphthoyl), Xm is p-oxybenzoyl chloride. 2-oxy-6-naphthoyl chloride, phenyl (p-oxybenzoate), phenyl (2-oxy-6-naphthoate), and for poly (p-benzamide), p-aminobenzoic acid chloride, and poly (p In the case of -mercaptobenzoyl), p-mercaptobenzoyl chloride or the like can be used as Xm.
[0011]
In the present invention, as the crystalline polymer Y that can be a matrix for the solid phase polymerization of Xm, when the raw material monomer Xm of the polymer whisker is mixed with Y, Xm can be uniformly dispersed in Y. A general material that is soluble and / or fusible with respect to Xm can be used, but it is necessary to have a melting point equal to or higher than the temperature at which solid-phase polymerization of monomer Xm proceeds. The solid phase polymerization of monomers varies considerably depending on the type of monomer used, but polymerization is possible at temperatures of 100 ° C or higher for active monomers such as acid chloride, and at temperatures of 200 ° C or higher for other carboxylic acids. Is possible. Examples of the crystalline polymer Y that falls into these categories include syndiotactic polystyrene, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyesters such as polyethylene-2,6-naphthalate, nylon 6, and nylon. Aliphatic polyamides such as 6,6, poly (m-phenylene isophthalamide), aromatic polyamides such as poly (p-phenylene terephthalamide), semi-aromatic polyimides such as poly (decamethylenepyromellitimide), In addition, poly (p-phenylene sulfide), poly (ether ether ketone), and the like can be used. Among these, polyolefin, aromatic polyamide, poly (p-phenylene sulfide) and the like are preferable from the practical aspect, and syndiotactic polystyrene and poly (m-phenylene terephthalamide) are particularly preferable.
[0012]
In the present invention, as a method of blending the crystalline polymer Y that can be a matrix for solid phase polymerization and the raw material monomer Xm of the polymer whisker, the following two methods are preferably mentioned.
1) Melt Y at a temperature equal to or higher than the melting point, quickly add Xm thereto, and knead in a short time with a stirring vessel or a twin screw extruder.
2) Y is dissolved or swollen in a suitable good solvent, Xm is added thereto, and the mixture is uniformly stirred and dissolved in a stirring vessel or a twin screw extruder, and then the solvent is removed by a dry or wet method.
[0013]
In the above method 1), the melt blending is performed under a shear stress, whereby uniform blend dispersibility of the monomer Xm in the matrix Y can be improved.
[0014]
In the present invention, the solid phase polymerization of the polymer whisker raw material monomer Xm blended with the crystalline polymer matrix may be performed at a temperature below the melting point of the crystalline polymer Y as the matrix polymer under standing conditions or with stirring. it can. Here, as described above, since the temperature at which the polymerization of the monomer Xm proceeds varies depending on the raw material monomer used, it is preferable to select the activity of the monomer in consideration of the melting point of the matrix polymer. In the present invention, when the crystalline polymer Y having a melting point of 100 to 200 ° C. is used, it is preferable to use an acid chloride as the monomer. When the melting point is 200 ° C. or more, an acetyl derivative or an active phenyl ester monomer is used. preferable. The solid phase polymerization may be performed under an inert gas atmosphere such as nitrogen or under a high vacuum. In either case, whisker polymerization can be carried out efficiently by carrying out the solid phase polymerization below the melting point of the matrix. Furthermore, the size and form (aspect ratio) of the whisker to be formed can be controlled by manipulating the polymerization time.
[0015]
The blend ratio of the monomer Xm to the crystalline polymer Y can be determined by the mechanical properties of the composite to be obtained. For example, the crystalline polymer Y is syndiotactic polystyrene and the monomer Xm is p-acetoxy. In the case of benzoic acid, the monomer Xm is 0.5 to 10% by weight, preferably 0.5 to 5% by weight, based on the crystalline polymer Y as a matrix. When the crystalline polymer is poly (m-phenylene isophthalamide) and the monomer is p-acetaminobenzoic acid, the monomer is 0.5 to 15% by weight, preferably 0.5 to 8% by weight, based on the matrix. is there. When the crystalline polymer is poly (p-phenylene sulfide) and the monomer is 2-acetoxy-6-naphthalenedicarboxylic acid, the monomer is 0.5 to 5% by weight, preferably 0.5 to 3% by weight based on the matrix. %. When the blend ratio exceeds the upper limit, it is difficult to obtain whiskers having an aspect ratio (> 10) that is preferred for growth of spherulites or the like over whisker crystal growth. Moreover, if it is less than the lower limit, the effect as a composite reinforcing material of the polymer whisker is not effectively exhibited.
[0016]
Further, in the production of the composite material of the present invention, an additive and a polymerization initiator may be added if necessary at the time of blending the monomers.
[0017]
【The invention's effect】
According to the present invention, since the polymer whisker is finely dispersed in the amorphous part of the crystalline polymer, it is possible to provide a polymer whisker composite in which the crystalline polymer is further strengthened. Since the crystalline polymer is blended with the polymer whisker-forming monomer before being put into practical use due to the composite reinforcement, the monomer is efficiently incorporated into the amorphous portion of the matrix. By subjecting this to solid phase polymerization at a relatively low temperature, the polymerized whisker can be used as a moldable composite material without collecting it again. This not only simplifies the production of polymer whiskers and the process of compounding to the to-be-reinforced material, but also prevents thermal deterioration of the crystalline thermoplastic polymer material, while still ensuring that the to-be-reinforced material is amorphous. The whisker polymerization and fine dispersion are allowed to proceed at the site, and as a result, a polymer whisker composite material in which the amorphous site is efficiently reinforced can be produced. In this way, the material reinforced with the composite whisker can exhibit mechanical properties corresponding to the fine structure, particularly high tensile strength and high impact resistance.
[0018]
The polymer whisker composite obtained by the present invention can be used for various molded products conventionally produced by injection molding using a crystalline polymer (for example, industrial materials such as automobile parts, ropes, sheets, films). Useful for.
[0019]
【Example】
Hereinafter, the present invention will be described in more detail with reference examples and examples. However, the present invention is not limited in any way by the following reference examples and examples. In the examples, “parts” represents “parts by weight” unless otherwise specified. The morphology of the polymer whiskers was observed with a scanning electron microscope (Hitachi S-510).
The results are summarized in Table 1 for each example.
[0020]
[Example 1]
<Production of polymer whisker complex by solid phase polymerization of p-acetoxybenzoic acid using syndiotactic polystyrene as matrix>
29.4 parts of syndiotactic polystyrene was placed in a 100 ml glass flask and melted at 270 ° C. in a nitrogen atmosphere. To this, 0.9 part of p-acetoxybenzoic acid was quickly added as a monomer and stirred and kneaded for 5 minutes. The homogeneous dispersion was cooled to room temperature and crystallized to prepare a monomer dispersion matrix. Next, 20 parts of this were pulverized to a particle size of about 1 mm, and again taken into a glass flask. This time, solid phase polymerization was performed at 230 ° C. for 24 hours in a nitrogen atmosphere, thereby syndiotactic polystyrene / poly (p-oxybenzoyl). A whisker = 98/2 (weight ratio) composite was obtained. The observation mode of the polymer whisker produced in the composite by a scanning electron microscope was obtained by extracting the matrix polymer with tetrahydrofuran and then collecting insoluble whiskers.
[0021]
[Example 2]
<Production of Polymer Whisker Complex by Solid Phase Polymerization of p-Acetaminobenzoic Acid Using Poly (m-phenyleneisophthalamide) as a Matrix>
A uniform dope solution was obtained by dissolving 29.4 parts of poly (m-phenyleneisophthalamide) in 100 ml of N-methyl-2-pyrrolidone with heating. To this was added 0.9 part of p-acetaminobenzoic acid as a monomer, and the mixture was uniformly dissolved by stirring. The blended solution was cast on a glass plate, dried at 150 ° C. under a nitrogen stream for 4 hours, and then dried at 100 ° C. and 1 mmHg for 4 hours to prepare a monomer-dispersed matrix film. Next, this was processed into a strip shape, and 20 parts thereof were again taken into a glass flask, and subjected to solid phase polymerization at 290 ° C. for 24 hours in a nitrogen atmosphere, thereby poly (m-phenyleneisophthalamide) / poly (p-benzamide). ) Whisker = 98/2 (weight ratio) composite was obtained. The whisker formed in the composite was observed with a scanning electron microscope by extracting the matrix polymer with NMP in a 10 wt% lithium chloride solution and then collecting insoluble whiskers.
[0022]
[Example 3]
<Production of polymer whisker complex by solid-phase polymerization of p-acetoxybenzoic acid using poly (m-phenylene isophthalamide) as a matrix>
In place of p-acetaminobenzoic acid of Example 2, 0.9 part of p-acetoxybenzoic acid was added, and poly (m-phenyleneisophthalamide) / poly (p-oxybenzoyl) whisker = 98/2 (by the same method). (Weight ratio) A composite was obtained, and the formed whisker was observed with a scanning electron microscope.
[0023]
The results of the above examples are summarized in Table 1 below. From the experimental results of these examples, the obtained polymer whisker composite has a monomer that has been efficiently incorporated into the amorphous part of the matrix, and can be solid-phased smoothly at a relatively low temperature while suppressing thermal degradation of the matrix. Polymerized. By such a method, whisker is separated and purified after polymerization, and is collected as a single whisker without solidifying the whisker and dispersing the crystalline polymer, which is a material to be reinforced, into a single part. It is clear that the amorphous part in the matrix polymer can be used as a composite that is efficiently strengthened.
[0024]
In addition, the above composite is used as a composite material that can be used repeatedly by recycling because the crystalline polymer is reinforced using whiskers that can be recycled without using glass fibers that are difficult to reuse. It is also an advantage to be able to do it.
[0025]
[Table 1]

[0026]
1) Synd.Pst: Syndiotactic polystyrene
PMPIA: Poly (m-phenylene isophthalamide)
2) p-AcOBA: p-acetoxybenzoic acid
p-AcABA: p-acetaminobenzoic acid

Claims (3)

A monomer capable of forming a polymer whisker is mixed with a crystalline polymer, and then the mixture is heated to a temperature below the melting point of the crystalline polymer to dissolve the amorphous polymer in the amorphous part. A method for producing a polymer whisker complex in which a polymer whisker is finely dispersed in an amorphous part of a crystalline polymer, wherein the monomer is solid-phase polymerized to form a polymer whisker. Monomers capable of forming whiskers are p-acetoxybenzoic acid, 2-acetoxy-6-naphthalenedicarboxylic acid, p-acetaminobenzoic acid, p-acetoxy-mercaptobenzoic acid, p-oxybenzoyl chloride, 2-oxy-6-naphtho Yl chloride, phenyl (p-oxybenzoate), phenyl (2-oxy-6-naphthoate), p-aminobenzoic acid chloride, p Manufacturing process, which is a mercapto benzoyl chloride. The monomer capable of forming the polymer whisker is p-acetoxybenzoic acid, 2-acetoxy-6-naphthalenedicarboxylic acid, p-acetaminobenzoic acid or p-acetoxy-mercaptobenzoic acid. A method for producing a polymer whisker composite.   3. The method for producing a polymer whisker composite according to claim 1, wherein the crystalline polymer is a polyolefin or an aromatic polyamide.