JPH10130493A - Nylon resin composition having low molding shrinkage and small warpage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for producing molded articles which exhibits low shrinkage and small warpage, by incorporating a specific fibrous xonotlite into a nylon resin and subjecting the resulting compound to melting and crystallization under pressure. SOLUTION: This composition is obtained by compounding 85 to 50wt.% of the total weight of the composition of a nylon resin with 15 to 50wt.% of a fibrous xonotlite having a BET specific surface area of 21m<2> /g or more, melting the resulting compound, and then crystallizing it from a molten state at a pressure of 80Mpa under conditions such that the ratio (S) of the decrease of specific volume which decrease occurs in connection with the crystallization satisfies the requirement: 0<S<=0.9. The ratio (S) of the decrease of specific volume means the ratio of the decrease in the case of the nylon resin composition to that in the case of the nylon resin itself. It is required that the fibrous xonotlite to be used satisfy the following relationships: 0.1μm<=D<0.5μm, 1μm<=L<5μm and 10<=L/D<20, wherein D and L represent an average fiber diameter and an average fiber length, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low molding shrinkage / low warpage nylon resin composition containing fibrous zonotolite. Molded products obtained using this resin composition have a low molding shrinkage and a small warpage, so they are widely used in applications requiring dimensional accuracy such as automotive materials, electric / electronic parts, and precision machine parts. be able to.

[0002]

2. Description of the Related Art As a method for reducing the molding shrinkage and warpage of a nylon resin, it is widely known to incorporate a plate-like filler such as mica, glass flake, talc, sericite, etc. No. 52953, JP-A-4-361027, etc.). However, the plate-like filler has a smaller effect of improving rigidity than the fibrous filler, and is not particularly suitable for applications requiring heat resistance. On the other hand, the addition of the fibrous filler to the nylon resin remarkably improves the rigidity, but causes a large anisotropy, so that a molded product obtained from the resin composition comprising the nylon resin and the fibrous filler is warped.

[0003] From such a viewpoint, the inventors of the present invention firstly used a fibrous zonotlite, which is a very fine fibrous filler, as a filler or reinforcing material to be mixed with a thermoplastic resin such as a nylon resin. A method using a filler (see Japanese Patent Application No. 6-313001) and a method using a reinforcing fiber (see Japanese Patent Application No. 6-313002) have been proposed.

[0004]

However, in the method of using the fibrous zonotolite and the platy filler in combination, the anisotropy of the obtained resin composition is reduced, but the molding shrinkage is rather increased. On the other hand, in the method in which the fibrous zonotolite and the reinforcing fiber are used in combination, the molding shrinkage decreases, but the anisotropy increases. As described above, these methods cannot simultaneously reduce both the molding shrinkage and the warpage in the obtained resin composition. Accordingly, an object of the present invention is to provide a nylon resin composition which has a small molding shrinkage and provides a molded product with a small warpage, which could not be solved by the conventional techniques as described above.

[0005]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to solve the above-mentioned problems, a fibrous zonotlite having a specific property (that is, having a specific specific surface area) is used, and a specific physical property obtained from it and a nylon resin is obtained. It has been found that the above object can be achieved by providing a nylon resin / fibrous zonotolite composition having (a rate of decrease in specific volume accompanying crystallization when crystallized from a molten state under a pressure of 80 MPa). Thus, the present invention has been completed.

That is, the first invention of the present invention is:
85 to 50% by weight of nylon resin based on the whole resin composition
And a fibrous zonotlite having a BET specific surface area of 21 m ² / g or more by nitrogen adsorption of 15 to 50% by weight, wherein the resin composition is in a molten state under a pressure of 80 MPa with respect to the nylon resin. When the rate of decrease in specific volume due to crystallization when crystallizing from is defined as ΔV / ΔV ₀ , this value is expressed by the following equation (I).

(Equation 2) This can be achieved by providing a low molding shrinkage / low warpage nylon resin composition characterized by satisfying the following.

According to a second aspect of the present invention, the fibrous zonotolite is 0.1 μm ≦ D <0.5 μm, 1 μm ≦ L <
5 μm and 10 ≦ L / D <20 (where D and L
Respectively indicate the average fiber diameter and the average fiber length of the fibrous zonotolite), which is achieved by providing the low molding shrinkage and low warpage nylon resin composition according to the first invention. it can.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
You. The fibrous zonotolite described in the present invention is zonotora
Ito (indicative formula: Ca₆Si ₆O₁₇(OH)_Two,Chemical formula:
6CaO.6SiO_Two・ H_TwoO) Needle-like crystalline substance
U. In the present invention, the value of the specific surface area is very important.
21m^Two/ G or more, preferably 30 m^Two/ G or more
(However, it is a measured value by the BET method by nitrogen adsorption)
Must. This value is 30m^TwoLess than / g
In the case of fibrous zonotolite, wettability with nylon resin
May be bad, especially 21m^TwoRatio less than / g
For fibrous zonotolite with a surface area, this wetting
To achieve the object of the present invention described above.
Can not be.

Further, in the present invention, the fiber shape of the fibrous zonotolite is, in particular, an average fiber length (L) of 1 μm ≦ L <5 μm and an average fiber diameter (D) of 0.1 μm ≦
D <0.5 μm, and the aspect ratio (L / D) is 1
Those satisfying the condition of 0 ≦ L / D <20 at the same time can be suitably used. When D is less than 0.1 μm or L is 5 μm or more, the fibrous zonotolite may be broken at the time of mixing and kneading the fibrous zonotolite and the nylon resin, while D may be 0.5 μm or more. Things and L are 1μ
If it is less than m, the effect of improving the mechanical strength of the resulting nylon resin composition by the fibrous zonotolite may not be sufficient. Further, when the L / D is less than 10, sufficient mechanical strength may not be obtained in the obtained nylon resin composition, and when the L / D is 20 or more, fibrous zonotolite is used. May be too small to be kneaded during the production of the nylon resin composition of the present invention.

As described in detail below, the fibrous zonotolite of the present invention having the specific properties described above can be produced, for example, by the production method described in Japanese Patent Application Laid-Open No. 6-128412, It is manufactured by blending a high-quality raw material with a specific ratio and performing a hydrothermal synthesis reaction.
Examples of the calcareous raw materials include quick lime, slaked lime, carbide slag, and the like, and those containing few impurities such as magnesium oxide are preferable. Examples of the siliceous raw materials include pulverized silica, silica sand and quartz, silicic acid, silicic acid anhydride, silica gel, diatomaceous earth, clay and ferrosilicon dust, and the like. A fine powder having a diameter of 10 μm or less is desirable. The mixing ratio (Ca / Si ratio) of these two is slightly smaller than the theoretical equivalent, and is preferably 0.8 to 0.99. Also,
The ratio of water to be mixed is desirably 5 to 40 times, preferably 8 to 30 times the total weight of the calcareous raw material and the siliceous raw material.

In the hydrothermal synthesis reaction, for example, the calcareous raw material, the siliceous raw material and water in the above-mentioned predetermined ratio are charged into an autoclave, and the mixture is usually stirred at 180 to 240 ° C. for 1 hour.
It may take up to 8 hours. In this case, a predetermined ratio of the calcareous raw material, the siliceous raw material and water may be previously mixed in a slurry state and then charged into the autoclave. The reaction temperature and the reaction time in the hydrothermal synthesis reaction are important factors. If the reaction temperature and the reaction time are out of the above ranges, the fibrous zonotolite having the specific specific surface area used in the present invention as described above cannot be obtained.

In the present invention, the fibrous zonotolite obtained by the above-mentioned production method further comprises a surface active agent and / or a surface active agent for further improving the reinforcing effect on a composition comprising a nylon resin described later. It is desirable to be treated with a coupling agent (hereinafter referred to as “surface treatment agent”). That is, the surface treatment agent is used for the purpose of improving the affinity of the fibrous zonotolite with the matrix resin, that is, the nylon resin, and the reinforcing effect, that is, further increasing the mechanical strength. Specifically, the following can be used.
As the surfactant, any of anionic, cationic, amphoteric and nonionic surfactants can be used. Examples of anionic surfactants include alkyl ether sulfates, dodecylbenzenesulfonates, and stearates, and examples of cationic surfactants include tetradecylamine acetate and alkyltrimethylammonium chloride. Examples of the agent include dimethylalkyl lauryl petaine, and examples of the nonionic surfactant include polyoxyethylene octadecylamine and polyoxyethylene lauryl ether. As the coupling agent, a silane coupling agent, particularly γ-aminopropyltrimethoxysilane, γ-
Aminopropyltriethoxysilane, N-phenyl-γ
-Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-
Aminosilane coupling agents such as β (aminoethyl) γ-aminopropyltriethoxysilane, N-β (aminopropyl) γ-aminopropylmethyldimethoxysilane, γ-dibutylaminopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane Others,
Examples include titanate-based coupling agents, aluminum-based coupling agents, chromium-based coupling agents, and boron-based coupling agents.

The addition amount of these surface treatment agents should be 0.1 to 10% by weight, preferably 0.5 to 8% by weight, based on the fibrous zonotolite (dry matter basis). When the addition amount is less than 0.1% by weight, the above-mentioned strength improving effect is not sufficient, and when the addition amount exceeds 10% by weight,
Even if the addition amount is increased, the above-mentioned strength improving effect hardly increases. When the amount of addition is in the range of 0.1 to 0.5% by weight, the above-mentioned strength improving effect may not be sufficient, and when the amount of addition is in the range of 8 to 10% by weight, the above-mentioned strength improving effect is not increased. It tends to be unsatisfactory.

In the present invention, as described above, the fibrous zonotolite slurry obtained by the hydrothermal synthesis reaction is extracted from the autoclave, and the fibrous zonotolite is subjected to a surface treatment. The surface treatment method is not particularly limited,
For example, the surface treating agent is added to the fibrous zonotolite slurry as it is or after adding an appropriate amount of water, and the mixture is mixed and stirred in a slurry state using an appropriate device.
Subsequently, excess water is filtered and separated by a centrifugal dehydrator or a filter press to obtain a cake-like fibrous zonotolite. In addition, the surface treatment may be performed by drying the fibrous zonotolite slurry and then using the surface treatment agent dissolved in a small amount of water or a solvent, a so-called dry treatment method, but the operation becomes complicated, Further, the effect of the surface treatment is small and there is no particular merit.

Next, the cake-like fibrous zonotolite to which the surface treating agent is attached as described above is dried, and when a coupling agent is used as the surface treating agent,
After further heat treatment, the fibrous zonotolite used in the present invention is obtained. The drying is performed by using a known dryer such as a hot air circulation dryer or an infrared heating dryer, and the drying is performed for 100 to 15 days.
It is preferable to carry out at a temperature of 0 ° C. for 20 to 30 hours until the water content of the fibrous zonotolite becomes 1% by weight or less. In addition, the heat treatment when a coupling agent is used as the surface treatment agent is performed at 100 to 150 ° C. and 20 ° C.
It is preferred to carry out the drying following the drying of the water under heating for up to 30 hours. Furthermore, the fibrous zonotolite used in the present invention may be granulated for the purpose of easily mixing and kneading with a nylon resin described later. Granular fibrous zonotolite is a cake-like fibrous zonotolite to which the above-mentioned surface treatment agent is attached, and has a diameter of 1 to 3
When molded into 8 mm granules, followed by drying and using a coupling agent as the surface treatment agent,
It is obtained by further performing a heat treatment. in this case,
The granulator is not particularly limited, and may be a known type such as a rotary vertical granulator, a rotary drum granulator, a rotary flat granulator, a screw extrusion granulator, and a roll extrusion granulator. A granulator can be used. Further, when the diameter of the granular fibrous zonotolite is out of the above range, mixing and kneading with a single-screw extruder or a twin-screw extruder becomes difficult when mixing and kneading with the nylon resin, and the roll or the Banbury mixer is used. The resin composition must be sequentially filled and mixed and kneaded, for example, so that the fibrous zonotolite is remarkably destroyed, resulting in a decrease in the mechanical strength of the resin composition obtained. In the present invention, in the production of granular fibrous zonotolite, the above-mentioned cake-like fibrous zonotolite is dried as it is and heat-treated as necessary to obtain a particle size of 5%.
It may be formed into granules by a method of crushing to about mm, but powder is likely to be generated and the bulk is somewhat large, which makes handling somewhat difficult.

As the nylon resin used in the present invention, known nylon resins can be used as long as they are crystalline nylon resins. For example, crystalline polyamides obtained by ring-opening polymerization of a cyclic aliphatic lactam having three or more rings,
Crystalline polyamides obtained by polycondensation of diamine and dicarboxylic acid, crystalline polyamides obtained by polycondensation of salt obtained from diamine and dicarboxylic acid, crystallinity obtained by polycondensation of ω-aminocarboxylic acid Examples thereof include polyamides and crystalline copolymerized polyamides obtained by copolymerizing two or more of these polyamide-forming monomer components. Alternatively, a mixture of two or more of these crystalline polyamides or crystalline copolymerized polyamides can also be used.

Examples of the diamine include hydrazine, ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, and the like. Dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine,
Aliphatic diamines such as 2-methylhexamethylenediamine, 3-methylhexamethylenediamine, 2-ethyloctamethylenediamine and 3-t-butylhexamethylenediamine; 1,3-diaminocyclohexane;
4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl)
Cyclohexane, isophoronediamine, piperazine, N
Alicyclic diamines such as -aminoethylpiperazine, 2,5-dimethylpiperazine, bis (p-aminocyclohexyl) methane and 2,2-bis- (4'-aminocyclohexyl) propane, and m-xylylenediamine and and aromatic diamines such as p-xylylenediamine.

On the other hand, the dicarboxylic acids include, for example, oxalic acid, succinic acid, glutaric acid, adipic acid,
-Methyladipic acid, 3-methyladipic acid, 3-t-
Butyl adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonandioic acid, decanedioic acid,
Undecandioic acid, dodecandionic acid, tridecandionic acid, tetradecandionic acid, pentadecandionic acid, hexadecandionic acid, eicosandioic acid, dimeric dicarboxylic acid of lindelic acid and dicarboxylic acid of dimeric oleic acid, etc. Aliphatic dicarboxylic acid, 1,2-
Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, and terephthalic acid;
Isophthalic acid, 5-t-butylisophthalic acid, 1,2-
Naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid Acid, 2,3-naphthalenedicarboxylic acid,
2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,3-anthracenedicarboxylic acid,
1,4-anthracene dicarboxylic acid, 1,5-anthracene dicarboxylic acid, 1,9-anthracene dicarboxylic acid, 2,3-anthracene dicarboxylic acid, 9,10-anthracene dicarboxylic acid, biphenyl-2,2′-dicarboxylic acid, Aromatic dicarboxylic acids such as biphenyl-2,3'-dicarboxylic acid and 3- (4-carboxyphenyl) 1,1,3-indanecarboxylic acid. And, as the salt obtained from the diamine and dicarboxylic acid, for example, ethylene diammonium adipate, tetramethylene diammonium adipate, tetramethylene diammonium pimerate, tetramethylene diammonium azelate, pentamethylene diammonium sebacate, hexamethylene Methylene diammonium adipate, hexamethylene diammonium sebacate, hexamethylene diammonium succinate, octamethylene diammonium adipate, octamethylene diammonium sebacate, nonamethylene diammonium adipate, nonamethylene diammonium sebacate, decamethylene diammonium Adipate, undecamethylene diammonium sebacate, dodecamethylene diammonium adipate, dodecame It can be mentioned the diamine and equimolar salt obtained from the above dicarboxylic acids, such as oven ammonium sebacate and p- xylylene ammonium sebacate.

Examples of the ω-aminocarboxylic acid include ε-aminocaproic acid, ω-aminoheptanoic acid, ω-aminononanoic acid, ω-aminoundecanoic acid and ω-aminododecanoic acid. As the cyclic aliphatic lactam having three or more members, for example,
ε-caprolactam, ω-enantholactam, α-pyrrolidone, δ-methylpyrrolidone, α-piperidone, ω-
Undecanelactam and ω-dodecalactam can be mentioned.

Therefore, specific examples include polysuccinamide (nylon 4), polycapramide (nylon 6), poly-ω-aminononanoic acid (nylon 9), polytetramethylene adipamide (nylon 46), and polyhexamethylene adzide. Aliphatic homopolyamides such as poamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecanoamide (nylon 612), polyundecaneamide (nylon 11), polydodecaneamide (nylon 12) , Polyhexamethylene terephthalamide (nylon 6T (T represents terephthalic acid component unit; the same applies hereinafter)), polymethaxylylene adipamide (nylon MXD6 (MXD
Represents an m-xylylenediamine component unit. The same applies to the following)), polymetaxylylene veramide (nylon MXD8), polymetaxylylene sebacamide (nylon MXD10), polyparaxylylene adipamide (nylon PXD6 (PXD is a p-xylylenediamine component unit) The same applies hereinafter)), semi-aromatic homopolyamides such as polyparaxylylenepimelamide (nylon PXD7), polyparaxylyleneazeramide (nylon PXD9), and polyparaxylylene sebacamide (nylon PXD10) And as copolymerized polyamides, nylon 6/66, nylon 6/11, nylon 6/12, nylon 6/610, nylon 6/612,
Nylon 66/610, Nylon 66/612, Nylon 6/66/610, Nylon 6/66/612, Nylon 6/66/11, Nylon 6/66/12, Nylon 6 / 6T, Nylon 6 / 6I (I , Isophthalic acid component unit, the same applies hereinafter), nylon 66 /
6T, nylon 66 / 6I, nylon 6T / 6I, nylon 6/11 / 6T, nylon 6/12 / 6T, nylon 6/11 / 6I, nylon 6/12 / 6I, nylon 66/11 / 6T, nylon 66 / 12 / 6T, nylon 66/11 / 6I, nylon 66/12 / 6I, nylon 6 / 6T / 6I, nylon 66 / 6T / 6I, nylon 11 / 6T / 6I, nylon 12 / 6T / 6I, nylon 6 / MXD6 , Nylon 66 / MXD6, nylon MXD6 / PXD6, nylon MXD7 / PXD7,
Nylon MXD9 / PXD9 and Nylon MXD10
/ PXD10 and the like. In addition, a mixture of these homopolyamides and copolymerized polyamides is also a specific example. In the present invention, among these, nylon 6, nylon 66, nylon 12, nylon 6/66, nylon 6/66/12, nylon 6
6 / 6T can be mentioned as a particularly suitable example. The nylon resin used in the present invention is not particularly limited in the type and concentration of the terminal group, or in the molecular weight and molecular weight distribution.

Further, within the range where the effects of the present invention are not impaired, various sub-materials usually blended with the resin to improve the properties and production of the nylon resin composition comprising the nylon resin and the fibrous zonotolite, That is, heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, lubricants, antiblocking agents, tackifiers, sealability improvers, antifogging agents, crystal nucleating agents, release agents, In addition to additives and modifiers such as impact modifiers, plasticizers, crosslinking agents, foaming agents, flame retardants, flame retardant aids, pigments, dyes, and fragrances, fillers and reinforcing materials can also be added. it can. As the filler or reinforcing material, for example, wood flour as an organic substance, pulp, and iron as an inorganic substance, whisker such as copper, gold, silver, aluminum, flakes, fiber or powdered metal, carbon black, graphite, Carbon fiber, activated carbon, carbon materials such as hollow spheres, silica, alumina, silica-alumina, titanium oxide, iron oxide, zinc oxide, magnesia, calcia, potassium titanate, various ferrites, basic magnesium sulfate, basic magnesium carbonate Oxides including other complex oxides, silicates such as talc, clay, mica, asbestos, rock wool and zinc silicate, hydroxides, carbonates, sulfates, phosphates, borates of various metals, Borosilicate, aluminosilicate, titanate, basic sulfate,
Glass materials such as glass fiber, glass hollow spheres, glass flakes, etc., such as basic carbonates and other basic salts;
Ceramics such as silicon carbide, silicon nitride, aluminum nitride, mullite and cordierite, and waste such as fly ash and microsilica are included. Furthermore, other thermoplastic resins, thermoplastic elastomers, rubbers, and the like can be blended, if necessary, in an amount that does not impair the effects of the present invention, and they can also be crosslinked.

In the present invention, the content of the fibrous zonotolite in the nylon resin composition comprising the nylon resin and the fibrous zonotolite is 15 to 50% by weight, preferably 20 to 40% by weight. It is necessary. When the content of the fibrous zonotolite is less than 15% by weight, the resulting nylon resin composition is not improved in mechanical strength and rigidity, which is not preferable. On the other hand, if the content is more than 50% by weight, the melt fluidity of the obtained nylon resin composition is lowered and molding becomes difficult, and the appearance of a molded product obtained from the nylon resin composition is unfavorably deteriorated. In order to reliably prevent the occurrence of these undesirable phenomena, the content of the above-mentioned fibrous zonotolite should be within the above-mentioned preferable range.

And, the nylon resin composition of the present invention comprises:
The components as described above, that is, the nylon resin and the fibrous zonotolite, and, preferably, are composed of the above-described composition of these components, and further have specific physical properties as shown below. is necessary. That is, with respect to the molded article obtained from the nylon resin composition of the present invention, the specific volume of the resin composition relative to the nylon resin alone decreases with crystallization when crystallized from a molten state under a pressure of 80 MPa. The rate must be in a certain range. FIG. 1 schematically shows a change in specific volume of the nylon resin composition or the nylon resin alone according to temperature when the nylon resin composition or the nylon resin alone is crystallized from a molten state. In FIG.
ΔV represents a decrease in specific volume of the nylon resin composition or the nylon resin alone due to crystallization. In the present invention, ΔV / ΔV _0, which is the rate of decrease in specific volume due to crystallization when the nylon resin composition is crystallized from a molten state under a pressure of 80 MPa with respect to the nylon resin alone.
Is the following formula (I), preferably the following formula (II)

[0024]

(Equation 3)

[0025]

(Equation 4)

(However, the above equation (I) and the equation (I
In I), ΔV and ΔV ₀ are each 80M
The specific volume (cm ³ / g) of the nylon resin composition composed of the nylon resin and the fibrous zonotolite and the nylon resin alone, which accompany crystallization when crystallized from a molten state under a pressure of Pa. Indicates a decrease value. ) Is required to be satisfied. The value of ΔV / ΔV ₀ is 0.9
If it is larger, the volume decrease accompanying the crystallization of the nylon resin composition from the molten state is large, and molding shrinkage and warpage of a molded article obtained from the nylon resin composition become remarkable, which is not preferable. In addition, when the value of ΔV / ΔV ₀ is in a range larger than 0.8 and smaller than 0.9, the above-described undesired phenomenon may occur.

Next, the nylon resin composition of the present invention can be produced as follows. That is, the nylon resin composition comprising the nylon resin and the fibrous zonotolite is produced by a known method. Generally, the above-mentioned predetermined amount of the nylon resin and the fibrous zonotolite are melt-kneaded using a kneader to obtain the nylon resin composition of the present invention. At this time, the melting and kneading temperature is 10 ° C. higher than the melting point of the nylon resin used.
Higher temperature, not higher than 60 ° C higher than the melting point, preferably higher than 10 ° C higher than the melting point, 40 ° C higher than the melting point.
It is preferable that the temperature is not higher than the high temperature. When a mixture of the nylon resins is used, a nylon resin having a high melting point may be selected from the nylon resins to be used. If the melt-kneading temperature is lower than the melting point of the nylon resin + 10 ° C., the melt viscosity of the nylon resin becomes too high in the kneading machine, and a portion having a temperature lower than the melting point of the resin is formed. Do
Poor kneading may occur. On the other hand, if the melting and kneading temperature is higher than the melting point of the nylon resin + 60 ° C., the resin is thermally decomposed or thermally degraded, which results in discoloration or deterioration in physical properties of the obtained nylon resin composition. In order to reliably prevent the occurrence of these undesired phenomena related to the melt-kneading temperature, the melt-kneading temperature should be within the above-mentioned preferable range.

Examples of the kneading machine include extruders such as a single screw extruder and a twin screw extruder, a twin screw continuous mixer, a Banbury mixer, a super mixer, a mixing roll,
Examples thereof include a kneader and a Brabender plastograph, and the nylon resin composition of the present invention is generally obtained as a pellet. As the kneader, an extruder is preferable among the above, and a twin screw extruder is particularly preferable.

Further, the addition and mixing order of these components at the time of melt-kneading the nylon resin and the fibrous zonotolite can be arbitrarily selected. For example,
Prior to melt-kneading, using a Henschel mixer, ribbon blender, tumbler blender, or the like, after pre-mixing the fibrous zonotolite with the nylon resin, the mixture may be supplied to a hopper of an extruder,
Only the nylon resin is supplied to the hopper of the extruder,
The fibrous zonotolite may be supplied from the middle of the extruder. In the production of the nylon resin composition, the above-mentioned various auxiliary materials can be simultaneously added, if necessary, from the hopper of the extruder or in the middle of the extruder.

The thus obtained nylon resin composition of the present invention is molded into a desired shape by a molding method such as injection molding, compression molding, or hollow molding. The injection molding method is the most typical. It is.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited by these Examples and Comparative Examples unless it exceeds the gist thereof. Absent. The methods for evaluating the physical properties of the nylon resin alone and the molded article obtained from the nylon resin composition described in the following Examples and Comparative Examples were performed according to the following methods.

(1) Specific volume of the nylon resin alone (cm
³ / g) using a reduced value Gnomix Research Co. PVT measuring apparatus, a single product of nylon resins used in producing the desired nylon resin composition by blending with fibrous xonotlite crystallization from the molten state Specific volume (cm
³ / g) was measured. In this measurement, about 1.1 g of the nylon resin alone was crystallized by lowering the temperature from 255 ° C. to 4 ° C./min under a pressure of 80 MPa. Then, ΔV shown in FIG. 1 was evaluated as a specific volume reduction value (ΔV ₀ ).

(2) Decrease in Specific Volume (cm ³ / g) of Molded Product The desired nylon resin composition is crystallized from a molten state under a pressure of 80 MPa in exactly the same manner as in the above item (1). The decrease in specific volume (cm ³ / g) was measured. Then, ΔV shown in FIG. 1 was evaluated as a specific volume decrease value (ΔV).

(3) Mold Shrinkage Rate of Molded Product Using a desired nylon resin composition, the size is 100 m in length.
A flat plate having a size of mx 100 mm wide x 3 mm thick was injection-molded and conditioned in a desiccator at 23 ° C for 48 hours. Therefore, the dimensions of the flat plate in the MD direction (flow direction) and the TD direction (perpendicular direction) were measured using a three-dimensional measuring instrument BX303 manufactured by Mitutoyo Corporation, and the shrinkage ratio with respect to the die size in each direction was measured. %).
Then, the molding shrinkage of the flat plate is calculated by the following equation (III).

[0035]

(Equation 5) Was evaluated as a value determined by

(4) Warpage of Molded Product A disk was injection-molded using a center-gate disk mold having a diameter of 200 mm and a thickness of 3 mm, and the condition was adjusted in a desiccator at 23 ° C. for 10 days. . Then, the amount of warpage of the disk was measured using a three-dimensional measuring instrument BX303 manufactured by Mitutoyo Corporation. When measuring the amount of warpage, place the disc on the measuring board, measure the maximum height difference,
By dividing by the diameter, it was evaluated as the amount of warpage (%).

Reference Example 1 As a calcareous raw material, quicklime (manufactured by Calceed Co., Ltd., Ca
430 g of siliceous raw material for agricultural use (a product of Japan General Co., Ltd., Blaine specific surface area: 7,000 cm ² / g, SiO ₂ purity: 97%) 4
70 g and 18 liters of tap water were charged into a 30 liter SUS316 autoclave equipped with a stirrer. Then, while stirring at a rotation speed of a stirrer of 80 rpm, the temperature was raised to a holding temperature of 220 ° C. at a rate of 2 ° C./min, and held at a holding temperature of 220 ° C. for 5 hours to perform a hydrothermal synthesis reaction. Thereafter, the mixture was allowed to cool over 10 hours or more with stirring to obtain a fibrous zonotolite slurry. When the X-ray diffraction of this slurry was measured, only zonotolite was identified.

Next, 920 g of the fibrous zonotolite slurry (based on solid content) was added to about 18 liters of tap water and a nonionic surfactant (polyoxyethylene octadecylamine, manufactured by NOF Corporation, trade name: Nimeen 204) ) 46 g (5% based on fibrous zonotolite solids)
% By weight) and surface-treated while dispersing with a homogenizer. The slurry was dehydrated with a nutschet to form a cake, and then formed into a diameter of φ3 mm using a granulator.
By drying at 0 ° C., a surface-treated granular fibrous zonotolite was obtained. The BET specific surface area of this granular fibrous zonotolite was measured by nitrogen adsorption, and the average fiber length and average fiber diameter were measured by a scanning electron micrograph. As a result, 39 m ² /
g, 3 μm and 0.2 μm (hence the aspect ratio: 15).

Example 1 Using a co-rotating twin-screw extruder (cylinder diameter: φ30 mm, model: PCM30, manufactured by Ikegai Iron Works Co., Ltd.) at 250 ° C. Same), nylon 6 (Ube Industries, Ltd.)
Manufactured by UBE Nylon 1013B) and 20 parts by weight of the fibrous zonotolite obtained in Reference Example 1 were melt-kneaded to prepare pellets of a nylon resin composition. However, at this time, the fibrous zonotolite was supplied from the first vent of the extruder using a screw feeder, and deaeration was performed from the second vent of the extruder.

Therefore, the nylon resin composition pellets thus obtained were vacuum-dried at 80 ° C. overnight,
Using the pellets, a decrease in specific volume (ΔV) associated with crystallization from a molten state under a pressure of 80 MPa was determined.
In addition, nylon 6 (manufactured by Ube Industries, Ltd., trade name: UBE)
Nylon 1013B) pellets were used to determine the specific volume reduction value (ΔV ₀ ) associated with crystallization from the molten state under a pressure of 80 MPa. From the specific volume reduction values (ΔV and ΔV ₀ ), the specific volume reduction rate (ΔV / ΔV ₀ ) of the nylon resin composition nylon 6 due to crystallization from the molten state under a pressure of 80 MPa is calculated. I asked. Table 1 shows the results. Next, using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., model: Nestal C250), cylinder temperature (however, the temperature of the nozzle head portion, the same applies hereinafter) 240 ° C. and mold temperature 80 ° C.
In the above, the above-mentioned pellets were injection-molded to produce flat and circular test pieces. Table 1 also shows the measurement results of the molding shrinkage and the warpage using these test pieces.

Examples 2 to 4 and Comparative Example 1 Nylon 6 and fibrous zonotolite were used in the proportions shown in Table 1, respectively, in place of 80 parts by weight of nylon 6 and 20 parts by weight of fibrous zonotolite. Except for this, the same operation as in Example 1 was performed. Reduction rate of specific volume due to crystallization from a molten state under a pressure of 80 MPa with respect to nylon 6 of a nylon resin composition (Δ
V / ΔV ₀ ) and the molding shrinkage and warpage of the molded product are shown in Table 1. In Comparative Example 1, the amount of warpage was 1.61%, which was significantly larger than that in the example (0.13 to 1.02%).

Comparative Example 2 The mixing ratio of nylon 6 was changed to 80 parts by weight to be 100 parts by weight, and the mixing ratio of fibrous zonotolite was changed to 20 parts by weight to be 0 parts by weight.
The same operation as in Example 1 was performed except that only nylon 6 was used and no fibrous zonotolite was used. 8 against nylon 6 of the nylon resin composition
Table 1 shows the results obtained for the specific volume reduction rate (ΔV / ΔV ₀ ) due to crystallization from the molten state under a pressure of 0 MPa, and the molding shrinkage and warpage of the molded product. The molding shrinkage and the amount of warpage of the molded product were 1.61 respectively.
% And 1.98%, both of which are in the case of the examples (molding shrinkage: 0.32 to 0.51%, warpage: 0.1%).
(3 to 1.02%).

[0043]

[Table 1]

[0044]

As is clear from the examples and comparative examples described above, the nylon resin composition provided by the present invention provides a molded article of a nylon resin having a small molding shrinkage and a small warpage. Therefore, automotive materials,
It can be widely used for applications requiring dimensional accuracy, such as electric / electronic parts and precision machine parts.

[Brief description of the drawings]

FIG. 1 is a specific volume (cm ³ ) when a nylon resin or a nylon resin composition of the present invention is crystallized from a molten state.
/ G) is a diagram schematically showing a change with temperature.

[Explanation of symbols]

ΔV Specific volume when the nylon resin or the nylon resin composition of the present invention is crystallized from a molten state (cm ³ /
g) reduction value

Claims (2)

[Claims] 1. A nylon resin 85 based on the whole resin composition.
~ 50% by weight, and the BET specific surface area by nitrogen adsorption is 21
a fibrous zonotlite having a m ² / g or more of 15 to 50% by weight, wherein the resin composition is crystallized from the molten state under a pressure of 80 MPa with respect to the nylon resin. The rate of decrease in specific volume due to
When V / ΔV ₀ , this value is expressed by the following equation (I). A low molding shrinkage / low warpage nylon resin composition characterized by satisfying the following. 2. The fibrous zonotolite is (1) 0.1 μm ≦ D <0.5 μm, (2) 1 μm ≦ L <5 μm and (3) 10 ≦ L / D <20 (where D and L are respectively , The average fiber diameter and average fiber length of the fibrous zonotolite) are simultaneously satisfied.