JP3115655B2 - Method for producing reshaped article containing liquid crystalline polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding resin composition comprising a composite of a thermoplastic resin and a liquid crystal resin. More particularly, the present invention relates to a remoldable molding resin composition.

[0002]

2. Description of the Related Art Conventionally, molded articles made of synthetic resin having high strength and high rigidity include those obtained by mixing glass fibers with a thermosetting resin, or those made of long fiber glass in a thermoplastic resin called a stampable sheet. What is obtained by shaping the mixture etc. into a predetermined shape is known. A high-strength and high-rigidity synthetic resin using carbon fiber instead of the glass fiber is also known.

Further, as a synthetic resin molded article having high strength and high rigidity in which glass fibers and carbon fibers are not mixed, as disclosed in JP-A-1-320128, a thermoplastic resin and a liquid crystal resin (liquid crystal polymer) are used. Strand obtained by extruding while stretching the composite material comprising the liquid crystal resin at a temperature equal to or higher than the liquid crystal transition temperature is cut into a length of 1 to 40 mm, and the obtained cut product is equal to or lower than the liquid crystal transition temperature of the liquid crystal resin. Is also known by extrusion at a temperature of.

Recently, it has been desired to recycle (re-mold) a synthetic resin body which has become a molded product from the viewpoint of resource protection and the like. When recycling a molded article made of a synthetic resin body, after crushing the synthetic resin body to obtain a crushed piece made of a synthetic resin, heating and melting the crushed piece,
Molding a synthetic resin material in a molten state into a molded product of a predetermined shape, or extruding a synthetic resin in a molten state to obtain a molding material, and then molding the molding material into a molded product of a predetermined shape It is.

Conventionally, when recycling a synthetic resin body having high strength and high rigidity, a fiber reinforced resin body obtained by mixing reinforcing fibers such as glass fiber and carbon fiber with a synthetic resin has been targeted. .

[0006]

However, when the above-mentioned fiber reinforced resin body is re-formed, the crushed pieces obtained by crushing the fiber reinforced resin body contain reinforcing fibers mixed in the synthetic resin body. Since the fibers are cut short, the reinforcing fibers remain cut even in the molding material obtained by reshaping. For this reason, the remolded product obtained by recycling had to be reduced in strength and rigidity as compared with the original molded product.

In view of the above, an object of the present invention is to prevent the strength and rigidity of a reshaped product obtained by reshaping a high-strength, high-rigidity synthetic resin body from lowering than the original synthetic resin body. Aim.

[0008]

That is, the present invention relates to a matrix resin which is polybutylene terephthalate and a liquid crystalline polymer having a higher melting point than the matrix resin.
A composite molded article comprising 0 to 70% by weight of a liquid crystalline polymer formed into fibers in the matrix resin is pulverized, and then the pulverized material is heated and melted at a temperature higher than the melting point of the liquid crystal polymer. After preparing the remolding material in a state of imparting orientation to the liquid crystal polymer molecules, the liquid crystal polymer fibers are formed by molding at a temperature equal to or higher than the melting point of the matrix resin and lower than the melting point of the liquid crystal polymer. The present invention provides a method for producing a reshaped product containing a liquid crystalline polymer, wherein the aspect ratio of the liquid crystalline compound is set to 3 or more.

[0009] Polybutylene terephthalate (PB) which is a matrix resin used in the remolded article of the present invention.
T) is commercially available. Specifically, as commercial products, for example, 1401 × 07 [manufactured by Toray Industries, Inc.], C7
000 (manufactured by Teijin Limited), Planac BT-100 (manufactured by Dainippon Ink and Chemicals, Inc.) and the like, and one or more of these may be used. The content of the matrix resin is preferably from 30 to 90% by weight based on the total weight of the resin composition. If the amount of the matrix resin is less than 30% by weight, the moldability of the resin composition will be reduced. If the amount exceeds 90% by weight, the strength of the molded article will be insufficient.

The reshaped product of the present invention contains a liquid crystalline polymer. The liquid crystalline polymer forms a fiber shape having an aspect ratio described later in the molded product, and serves as a reinforcing material for the molded product. Such a liquid crystalline polymer has a higher melting point than that of the matrix resin, and preferably has a higher melting point by 20 ° C. or more. If the melting point is lower than that of the matrix resin, the liquid crystalline polymer does not become fibrous in the molded product, the orientation is not constant, and sufficient strength cannot be obtained. As the liquid crystal polymer, various conventionally known ones can be applied, and there is no particular limitation. Various types of liquid crystal polymers are known, and particularly preferably used in the present invention are thermoplastic liquid crystal polyesters and liquid crystal polyester amides. Particularly preferred examples of such a material include those described below. That is

[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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Here, Δni = 100. It is particularly preferable that ni of each structural formula is 4 or more.

In each formula, various substituents such as halogen may be added. These are particularly preferred because they are easily melt-molded with the modified polyester of the present invention. Moreover, it is easy to make a composite fiber having high strength and high elastic modulus.

Similarly, a conventionally known liquid crystal polyesteramide can be applied, and the liquid crystal polyesteramide is not limited at all. Particularly preferred are those represented by the following structural formulas. That is

[0019]

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[0020]

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[0021]

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Here, Δni = 100 in each structural formula. It is particularly preferable that ni of each structural formula is 15 or more. In addition, various substituents such as halogen may be added to each formula. These compounds have melt moldability and high strength similarly to the liquid crystal polymer composed of polyarylate. The content of the liquid crystalline polymer is 3 to 70% by weight based on the total weight of the resin composition. If the content is less than 3% by weight, sufficient strength cannot be imparted to the molded product, and if it exceeds 70% by weight, the moldability of the resin composition is reduced.

The resin composition of the present invention may contain other additives such as a light stabilizer, an antioxidant and a plasticizer.

The resin composition of the present invention is once heated to a molten state, that is, a temperature higher than the melting point of the liquid crystalline polymer, and is molded or formed into a molding material in a state of imparting orientation to polymer molecules. The state of imparting the orientation to the polymer molecule is generally given by a method such as extrusion molding, injection molding or the like. Molding may be performed directly by this method to obtain a molded article having high orientation (molecular orientation). However, usually, after extrusion molding, it is made into a pellet-like molding material. Using this molding material, it is again melted and molded by an extruder, an injection molding machine or the like. It is preferable that the re-melting temperature be higher than the melting point of the matrix resin and lower than the melting point of the liquid crystal polymer, since the liquid crystal resin maintains a fibrous state. A flat material may be used as the molding material. In this case, the molding material plates may be stacked and molded in the mold. In particular, by making the orientation directions the same or different, the properties of the molded article can be changed.

The fibrous liquid crystalline polymer composited in the reshaped product has an aspect ratio (ie, length / thickness) of 3 or more,
Preferably, it has 10 or more.

[0026]

According to the present invention, a reshaped product is obtained by using the above-mentioned shaped material as a raw material, pulverizing the material as necessary, and re-melting and re-molding according to the above-mentioned production method. The fibrous liquid crystalline polymer in the remolded product thus obtained is essentially the same as that in the raw molded product, and has an aspect ratio of 3 or more. Substantially equivalent. Such reshaped articles can also be reshaped any number of times, giving reshaped articles with substantially no loss in strength.

[0027]

The present invention will be described below in more detail with reference to examples. First, as a liquid crystal resin, Vectra A950 manufactured by Polyplastics Co., Ltd. (aromatic polyester, liquid crystal transition temperature:
(Approximately 280 ° C.) and a PBT of 14 manufactured by Toray Industries, Inc.
Using 01 × 07, the two were mixed at a predetermined ratio to obtain a liquid crystal resin composite material.

Next, the above liquid crystal resin composite material was initially extruded. In this case, the extrusion conditions were as follows: a twin-screw extruder (screw diameter: 3) manufactured by Plastic Engineering Laboratory Co., Ltd. was used as the extruder.
0 mm), a resin temperature of 290 ° C., a screw rotation speed of 100 rpm, a die diameter of 2 mm, and a shear rate of 17 mm.
At 00 sec ⁻¹ , the stretching ratio was set to 2 times. And
The liquid crystal resin composite material was extruded while being stretched to obtain a strand-shaped initial molding material having a diameter of 1.4 mm for a test, and a part of the initial molding material was cut into a length of 3 mm. Thus, an initial pellet material was obtained.

Next, the initial pellet material was injection molded to obtain a liquid crystal resin composite. In this case, the injection molding conditions were such that a 220 Ton injection molding machine manufactured by Toshiba Machine Co., Ltd. and a test piece mold were used, and the resin temperature was set to 240 ° C. Further, in this case, the injection molding machine and the spiral flow type (semicircular with a diameter of 6 mm) mold were used, and the resin temperature was set at 2.
A fluidity evaluation test was conducted at 40 ° C. and an injection pressure of 1000 kg / cm ² .

Next, the liquid crystal resin composite was pulverized with a pulverizer of V-360 manufactured by Horai Co., Ltd., and the length was 3 to 4 mm.
After obtaining a crushed piece of the above, the crushed piece is recycled and extruded to obtain a strand-shaped recycle molding material having a diameter of 1.4 mm for a test, and a part of the recycle molding material has a length of: It was cut into 3 mm to obtain a recycled pellet material.
The extrusion molding conditions in this case were the same as in the case of the initial extrusion molding.

Next, a tensile test was performed on the strand-shaped initial molding material and the recycled molding material. A universal testing machine (Autograph) manufactured by Shimadzu Corporation was used as a measuring machine, and the tensile speed was set to 20 mm / min.

FIG. 1 shows the results of a tensile test performed on the initial molding material and the recycled molding material.
In the region where the content of the liquid crystal resin exceeds 10%, fibrosis of the liquid crystal resin occurs, and the tensile strengths of the both are substantially the same over the entire range of the content of the liquid crystal resin. It was confirmed that the strength did not decrease in spite of the re-molding of the synthetic resin.

FIG. 2 shows the relationship between the liquid crystal resin content and the flow length ratio. It is clear that when the liquid crystal resin content exceeds 70%, the fluidity is extremely reduced, and it is difficult to use as a molding material. Became. From the above considerations, when PBT is used as the thermoplastic resin, the content of the liquid crystal resin is 10 to 7
Preferably, it is within the range of 0%.

The morphological observation of the material for initial molding and the material for recycling molding by an electron microscope (SEM) showed that when the content of the liquid crystal resin was 10%, most of the liquid crystal resin was granular and some Was fibrous.
When the content of the liquid crystal resin was 20%, the liquid crystal resin was fibrous. From this result, it can be understood that, when the content of the liquid crystal resin is 10% or more, the liquid crystal resin is fiberized and the tensile strength is improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of a tensile test on a material for initial molding and a material for recycling molding obtained in Examples.

FIG. 2 is a graph showing a liquid crystal resin content and a flow length ratio in a molded product obtained in an example.

────────────────────────────────────────────────── (5) References JP-A-5-70700 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/00 C08L 67/00-67 / 04 C08L 77/12

Claims (3)

(57) [Claims] 1. A molded article containing a matrix resin of polybutylene terephthalate and 10 to 70% by weight of a liquid crystalline polymer having a higher melting point than the matrix resin, wherein the liquid crystalline polymer is fiberized in the matrix resin. After the composite molded article is pulverized, and then the pulverized material is heated and melted to a temperature higher than the melting point of the liquid crystalline polymer to prepare a remolding material in a state of imparting orientation to the liquid crystalline polymer molecules. By molding at a temperature not lower than the melting point of the liquid crystalline polymer but higher than the melting point of the resin, the aspect ratio of the liquid crystalline polymer fibrous liquid crystal is set to 3 or more. Manufacturing method of molded article. 2. The process according to claim 1, wherein the liquid crystalline polymer fibrous liquid crystal of the reshaped product has an aspect ratio of 10 or more. 3. The method according to claim 1, wherein the melting point of the liquid crystalline polymer is higher than that of the matrix resin by 20 ° C. or more.