JP2000256473A - Filled resin molding containing filler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a filled resin molding containing a filler, having improved surface properties and prevented in deterioration in toughness by making a filler in a molding distributed in such a manner that the concentration of the filler, which has a specific gravity higher than that of the resin, is higher in the surface region that in the inner region. SOLUTION: A composition containing a monomer or an oligomer, 1-50 wt.%, particularly, 5-30 wt.% filler having a specific gravity higher than that of the resin to be formed, and optionally, a catalyst and a polymerization initiator is poured into a rotating mold and polymerized to a viscosity of 1-1,000 Pa.s, particularly, 10-100 Pa.s while it is centrifugally pushed against the inner wall of the mold to form a surface region having a thickness of 1-50 mm. Next, a composition containing a filler in such an amount that the ratio of the filler content of the surface region to that of the inner region is 10/9 to 10/0, a monomer or an oligomer, and, optionally, a catalyst and a polymerization initiator is poured into a mold and polymerized to obtain a molding in which the concentration of the filler having a specific gravity higher than that of the resin is higher in the surface region than in the inner region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded article, and more particularly to a resin molded article formed by monomer casting.

[0002]

2. Description of the Related Art In order to improve the surface properties of a resin molding, molding is often performed after adding various agents to the resin.

[0003]

In the case of an agent relating to the physical properties of the surface of a molded article, the agent present inside the molded article does not function and is useless, and may adversely affect other physical properties of the molded article. For example, when an agent such as carbon black or graphite is mixed with a molding material to prevent the molded article from being charged and molded, the agent present inside the molded article lowers the toughness of the molded article. For example, in the case of a roll for transporting a heavy object, this reduction in toughness is a major problem.

[0004]

SUMMARY OF THE INVENTION Many fillers have a higher specific gravity than resins. Therefore, a centrifugal force is applied to the mold before the molding composition containing the filler in the mold is solidified, and the filler is transferred to the surface of the molded article by the action of the centrifugal force. However, when a centrifugal force is simply applied to the filler-containing composition, most of the filler reaches the surface of the mold, and the ratio of the filler is disadvantageously increased on the surface of the formed molded article. As a result, the surface of the molded article becomes weak to impact, and the filler is liable to fall off.

[0005] The surface area of the molded body, preferably 1 mm from the surface
The filler is present at a relatively high content in the depth range of ５０50 mm, in particular up to 10-30 mm, the filler is present at a relatively low content in the inner region and between this surface region and the inner region The present invention has found a method for producing a resin molded article having sufficiently high tensile strength, and has completed the present invention.

That is, according to the present invention, in an integrally molded resin article containing a filler, a filler having a specific gravity higher than that of a resin is higher in a surface area of the molded article than in an inner area of the molded article. And a resin-integrated molded body.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As a method for producing a molded article of the present invention, a monomer casting method in which a monomer or an oligomer is polymerized in a rotating mold is preferable, and a monomer is added so that a filler has a desired distribution. And the centrifugal force is appropriately controlled. As the embodiment, there are the following three methods.

(1) A small amount of a first composition containing a monomer or oligomer (hereinafter simply referred to as a monomer), and optionally a catalyst and a polymerization initiator, is poured into a rotating mold. The composition is pressed against the inner wall of the mold by centrifugal force to form a layer. In this state, a polymerization reaction is performed, and the viscosity of the composition increases, but when the polymerization has not yet progressed to a solid state, for example, the viscosity is 1 to 1,000 Pa · s,
In particular, when the pressure reaches 10 to 100 Pa · s, the second composition containing a filler, a monomer, and if necessary, a catalyst and a polymerization initiator is injected, and the polymerization is further continued. The filler moves in the circumferential direction due to centrifugal force and moves in the circumferential direction in the first composition, but since the first composition has already thickened, the movement of the filler therein is resisted. Receive. Therefore, most of the filler does not reach the surface of the mold,
Suitable thickness, preferably 1 to 50 mm, especially 10 to 30
In the region of mm, a surface area with a high filler content remains, while in the internal area the filler content is low. It should be noted that the rotational speed of the mold at the time of injecting the first composition may be different from that at the time of injecting the second composition.

Before the polymerization of the first composition is completed, the second composition is added and the polymerization of the two is advanced. Therefore, the polymerization proceeds between the first composition and the second composition, and the two are slightly mixed. Since they are mixed and polymerized, the tensile strength at the boundary between the two compositions does not become extremely low, and the composition sufficiently withstands use. The tensile strength at the boundary is preferably at least 50% of the tensile strength without such a boundary.

(2) A small amount of the first composition containing a filler, a monomer, and, if necessary, a catalyst and a polymerization initiator is injected into a rotating mold to cause a polymerization reaction. The centrifugal force at this time is selected to be sufficient to press the composition against the inner wall of the mold, but not so large that most of the filler reaches the inner wall of the mold. At the point where the polymerization has proceeded and the viscosity of the composition has increased, but has not yet progressed to solids, a second composition containing the monomer, optional catalyst and polymerization initiator is poured into the mold. Continue the polymerization. Then, similarly to the above (1), a molded body having a high filler content and a surface region of an appropriate thickness is obtained. The rotational speed of the mold when injecting the first composition may be different from that when injecting the second composition, especially when the first composition is already thickened and further significant migration of the filler. If there is no, the latter can be made larger than the former. Then, a large centrifugal force can be applied to the second composition (having a small radius), so that a clean circular shape can be obtained.

(3) A composition containing a filler, a monomer, a catalyst and, if necessary, a polymerization initiator is poured into a rotating mold in an amount required for a finished molded product. The centrifugal force at this time is sufficient to press the composition against the inner wall of the mold,
The filler is selected so small that it hardly migrates in the circumferential direction. When the polymerization proceeds and the viscosity of the composition increases, the rotational speed of the mold is increased to increase the centrifugal force, and the filler is transferred in the outer peripheral direction. Since the composition is already thickened, most of the filler does not reach the wall of the mold, and a molded body having an appropriate thickness and a high filler area as in (1) above is obtained. Can be

In any of the above (1), (2) and (3), the specific gravity, shape and addition amount of the filler, centrifugal force at each stage, timing of injection of the second composition (increase of the first composition) By manipulating the degree of viscosity, the polymerization reaction rate (temperature, catalyst), etc., the thickness of the surface region and its filler content can be adjusted and can be easily confirmed by experiments.

The content of the filler in the surface region depends on the type of the filler, but is preferably 1 to 50% by weight, more preferably 5 to 30% by weight, especially 10 to 20% by weight. The ratio of the filler content in the surface region to the filler content in the inner region is preferably from 10: 9 to 10: 0, more preferably from 10: 5 to 10: 0. The filler content in the inner region is preferably less than 5% by weight, more preferably less than 1% by weight, so that the overall physical properties of the molded article, such as toughness, are not adversely affected by the filler.

The boundary between the surface area and the internal area is where the filler content changes abruptly and can be determined by observing the cross section of the molded article or measuring the filler content according to, for example, ASTM D1603-68. . The thickness of the surface region is preferably 1 to 50 mm, more preferably 5 to 2 mm.
5 mm.

Examples of the filler include graphite, carbon black, and metal powder for antistatic purposes. For example, non-oriented carbon black, white carbon, colloidal calcium carbonate, heavy calcium carbonate and uniaxially oriented trait calcium carbonate, dry zinc oxide, halloyside, asbestos powder, cellulose powder, biaxially oriented Certain kaolinite, sericite, graphite, talc, mica, waxite powder, basic magnesium carbonate, and the like.

The monomers or oligomers used are preferably those which polymerize relatively quickly at atmospheric pressure to form polymers. As polymers to be obtained, polyamides,
(Unsaturated) polyester, polystyrene, poly (meth)
Examples include acrylic acid (ester), polyacetal, epoxy resin, polyurethane, phenolic resin, urea-melamine resin, and copolymers thereof. Particularly preferred is polyamide, and a cyclic amide monomer or oligomer is used as a raw material for polymerization.

As the cyclic amide, ω having 4 to 12 carbon atoms is used.
Lactam, γ-butyrolactam, ε-caprolactam, ω-enantholactam, ω-capryloractam, ω
-Laurolactam and the like, with ε-caprolactam being particularly preferred. These cyclic amides can be used alone or as a mixture of two or more. Examples of the comonomer that can be copolymerized with the cyclic amide include diamines such as hexamethylenediamine, 1,4-diaminobutane, and p-phenylenediamine; and dicarboxylic acids such as diol, adipic acid, sebacic acid, succinic acid, terephthalic acid, and isophthalic acid. Examples include acids, aminocarboxylic acids such as aminolauric acid or laurolactam or lactams thereof, and cyclic esters.

The cyclic ester includes ω-lactone, β-propiolactone, β-butyrolactone, β-valerolactone, δ-valerolactone, β-valerolactone having 3 to 12 carbon atoms.
Methyl-δ-valerolactone, δ-caprolactone, ε
-Caprolactone, α-methyl-ε-caprolactone,
Examples include ω-enantholactone, ω-caprylolactone, ω-laurolactone and the like, and particularly preferred is ε-caprolactone. These cyclic esters can be used alone or as a mixture of two or more.

The polymerization of the resin may be carried out according to a known method. For example, a polyamide resin can be produced by a monomer casting method using a conventionally known anion polymerization catalyst. That is, the anion polymerization is carried out by heating the substantially anhydrous monomer to a temperature higher than the melting point of the monomer and lower than the melting point of the polymer in the presence of the anion polymerization catalyst and the polymerization promoter.

The polymerization catalyst and the polymerization co-catalyst may be those usually used. Examples of the polymerization catalyst include alkali metals, alkaline earth metals and hydrides, oxides, hydroxides, carbonates, alkylates, alkoxides, hydrides of these metals. Grignard compounds and reaction products thereof with ω-lactam and the like, and more specifically, lithium, sodium, potassium, magnesium, calcium, lithium hydride, sodium hydride, potassium hydride, sodium oxide, potassium oxide, Sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, methyl sodium, ethyl sodium, methyl potassium, ethyl potassium, sodium methylate, sodium ethylate, potassium methylate, potassium ethylate, methyl magnesium bromide, ethyl methyl Neshi Umm bromide, and the like. These polymerization catalysts can be used alone or as a mixture of two or more, and the amount of the catalyst is usually 0.02 to
2.0 mol%.

Examples of the polymerization co-catalyst include isocyanates, acyl lactams, carbamido lactams, isocyanurate derivatives, acid halides, urea derivatives and the like. More specifically, n-butyl isocyanate, phenyl isocyanate Octyl isocyanate, tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, m-xylene diisocyanate, 4,4′-diphenylmethane diisocyanate, N-acetyl-ε-caprolactam,
Examples include 1,6-hexamethylenebiscarbamidocaprolactam, triallylsocyanurate, terephthaloyl chloride, 1,3-diphenylurea and the like. These polymerization co-catalysts can be used alone or as a mixture of two or more thereof, and the amount of the co-catalyst added is usually 0.02 to 2.0 mol%.

The raw material for polymerization may further contain, if necessary, conventional components such as stabilizers, dispersants, and antibacterial agents.

The molded product obtained by the present invention is, for example, a hollow or solid roll, but is not limited thereto.

[0024]

EXAMPLES Graphite (Showa Denko KK, UFG-10, specific gravity 2.2) was used as a filler. E-caprolactam (specific gravity 0.98) was used as a monomer, and sodium hydride was used as a catalyst.

The obtained molded pipe was sliced in a radial direction and a horizontal direction with a width of 5 mm to obtain a sample. The graphite content of each sample was measured according to ASTM D1603-68.

[0026]

Example 1 The following two kinds of raw materials were prepared,
The temperature was adjusted to ° C. First raw material: 24 kg of ε-caprolactam + 480 g of sodium hydride Second raw material: 18 kg of ε-caprolactam + 360 g of sodium hydride + 3 kg of graphite -Caprolactam). A cylindrical mold having an inner diameter of 350 mm and a length of 1000 mm is rotated at 500 rpm in a 160 ° C. oven while keeping the center of rotation of the circle horizontal. Here, the first
The ingredients were poured within 200 seconds. One minute after completion of the injection of the first raw material, the second raw material was poured into the same mold at the same mold rotation speed as above. The rotation was further continued for 20 minutes to complete the polymerization of the first and second raw materials. Removed pipe-shaped molded product (outer diameter 35
0 mm, inner diameter 300 mm)
There was a clear color boundary at the point of mm. Diameter 350-33
The graphite content between 0 mm is 15% by weight and the diameter 33
The graphite content between 0 and 300 was less than 0.1% by weight.

[0027]

Comparative Example 1 In Example 1, except that the interval between the completion of the injection of the first raw material and the injection of the second raw material was set to 2 minutes.
Example 1 was repeated. In the section of the removed molding, there is a clear color boundary at the point of 323 mm in diameter, but contrary to Example 1, the graphite content between 350 and 323 mm is 0.1% by weight and the diameter is 323 to 33.
The graphite content between 0 mm was 15% by weight.

[0028]

Example 2 The following two kinds of raw materials were prepared,
The temperature was adjusted to ° C. First raw material: 18 kg of ε-caprolactam + 360 g of sodium hydride + 3 kg of graphite Second raw material: 24 kg of ε-caprolactam + 480 g of sodium hydride Each raw material was charged with 0.3% by weight of tolylene diisocyanate (TDI) when injected into a mold. -Caprolactam). A cylindrical mold having an inner diameter of 350 mm and a length of 1000 mm is rotated at 20 rpm in a 160 ° C. oven while keeping the center of rotation of the circle horizontal. Here, the first raw material was poured within 200 seconds. 1 from the completion of the injection of the first raw material
After 50 minutes, the second raw material was poured into the mold at a mold rotation speed of 500 rpm. Continue rotating for another 20 minutes
The polymerization of ~ 2 raw materials was completed. In the cross section of the pipe-shaped molded product (outside diameter: 350 mm, inside diameter: 300 mm), there was a clear color boundary at a place with a diameter of 330 mm. The graphite content between 350 and 330 mm in diameter was 15% by weight, and the graphite content between 330 and 300 in diameter was less than 0.1% by weight.

[0029]

Example 3 42 kg of ε-caprolactam, 840 g of sodium hydride and 3 kg of graphite were mixed, and 13
Adjust the temperature to 0 ° C. Add 130g of TDI to this,
The solution was poured within 200 seconds into a cylindrical mold having an inner diameter of 350 mm and a length of 1,000 mm, which was previously kept in an oven at 160 ° C., kept at the center of the circle horizontally, and rotated at 20 rpm. After one minute, the rotation speed was increased to 500 rpm. Removed pipe-shaped molded product (outer diameter 350 mm, inner diameter 300 m
In the cross section of m), there was a clear color boundary at a point of 330 mm in diameter. The graphite content between 350 and 330 mm diameter was 15% by weight and the graphite content between 330 and 300 diameter was less than 0.1% by weight.

[0030]

According to the present invention, since the filler is present in a high content in the surface region of the molded product and low in the internal region, the surface physical properties of the molded product are improved, and on the other hand, the physical properties of the whole molded product due to the filler, such as toughness, are improved. The adverse effects, such as a decrease in the amount, are avoided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 77/02 B29C 67/16 101/16 C08L 101/00 // B29K 77:00 105: 16 B29L 23: 00 31:08 F term (reference) 4F071 AA54 AB03 BA03 BB12 BB13 BC05 BC06 4F205 AA29L AB11 AB18 AG08 AG14 AH04 GA01 GB01 GC04 GF01 GF02 GF27 GN01 GN13 4J002 BC021 BG021 CB001 CC031 CC161 CC181 CD001 CF211 CK01 DA02

Claims (8)

[Claims] Claims: 1. In an integrally molded resin article containing a filler, a filler having a specific gravity higher than that of the resin is present at a higher content in a surface area of the molded article than in an inner area of the molded article. A resin integrated molded article characterized by the following. 2. The filler is graphite or carbon black, and has a filler content of 1 to 50 in the surface region.
The resin-integrated molded product according to claim 1, which is in terms of% by weight. 3. The resin molded article according to claim 1, wherein the ratio of the filler content in the surface region to the filler content in the inner region is 10: 9 to 10: 0. 4. The filler content in the inner region is 1% by weight
The resin-integrated molded product according to any one of claims 1 to 3, which is less than 4. 5. The resin integrated molded article according to claim 1, wherein the thickness of the surface region is 1 to 50 mm. 6. The monomer according to claim 1, which is formed by monomer casting.
6. The resin integrated molded article according to any one of items 5 to 5. 7. The method according to claim 6, wherein the monomer is a cyclic lactam.
The resin-integrated molded article according to the above. 8. The resin integrated molded article according to claim 1, wherein the molded article is a hollow or solid roll.