JPH1087843A - Resin pellet mixture - Google Patents

Abstract

(57) [Summary] A resin pellet which is excellent in moldability and provides a molded product having high mechanical strength. A mixture of a resin pellet having an average volume (Va) and a resin pellet aggregate (b) having an average volume (Vb), wherein Va / Vb is 1.01 to 10.0. mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding resin excellent in fluidity, mechanical properties, moisture and heat resistance and color tone, and more particularly to a resin pellet mixture which has a good biting property in molding property and can shorten a molding cycle. Parts, electric and electronic parts, especially plugs, coil bobbins, sockets, switches, tuner parts, relays, capacitors, terminal boards,
Bulb, fuse case, flyback transformer case, connector, motor brush holder, lamp socket, rear end panel, distributor cap, ignition coil, fuel pump,
It is a resin pellet mixture useful for applications requiring high cycleability and thin-walled mechanical properties, such as transmission valves, carburetor parts, especially connectors for automobile parts.

[0002]

2. Description of the Related Art Conventionally, in order to shorten the molding cycle of injection molding (higher cycle), a method of improving the crystallization speed of a resin has been adopted. For example, as a method of improving the crystallization speed of a resin, it is common to add a nucleating agent (such as talc) or a plasticizer (higher fatty acid) to the resin.

[0003]

However, in this method, the toughness of the resin is greatly reduced and the original performance of the resin cannot be exhibited, or unnecessary gas is generated at the time of injection molding to deteriorate the working environment and mold contamination. There was a problem.

Accordingly, an object of the present invention is to provide a method for shortening the injection cycle (high cycle) without impairing the inherent properties of the resin.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention.

That is, the present invention provides: "A mixture of a plurality of types of resin pellets having different average volumes, wherein the average volume (Va) of the resin pellet aggregate (a) having the largest average volume and the resin pellet aggregate (b) having the smallest average volume are obtained. Average volume (Vb) ratio (V
a / Vb) is a resin pellet mixture of 1.01 to 10.0. 1. "The weight ratio (a / b) of the resin pellet aggregate (a) to the resin pellet aggregate (b) is 99.9 / 0.1 to 0.1.
A resin pellet mixture having the characteristics of 1 above, wherein the mixture is 1 / 99.9. 2. 3. The resin pellet mixture as described above, wherein the resin of the resin pellets contains a thermoplastic resin. "A resin pellet mixture having the above three characteristics, wherein the resin of the resin pellet contains a polyester resin or a polyester resin composition.

[0007] 5. 5. A resin pellet mixture having the above-mentioned characteristics, in which the polyester resin is polybutylene terephthalate. "Large resin pellet aggregate (a) (average volume is V
a) and a small aggregate of resin pellets (b) (average volume is Vb). (However, Va / Vb is 1.
01 to 10.0. ) ", 7. "The weight ratio of resin pellet aggregate (a) and resin pellet aggregate (b) (a /
b) The method for producing a resin pellet mixture having the above-mentioned characteristics, wherein the relationship is 99.1 / 0.1 to 0.1 / 99.1. And 8. "A method for producing the resin pellet aggregates (a) and (b) is that, after melt-mixing a polyolefin and an unsaturated carboxylic acid and / or a derivative thereof, the polyester resin is further melted while maintaining the molten state. A method for producing a pellet mixture having the above characteristics, which is to be pelletized after mixing. "

According to the present invention, a plurality of types of pellet aggregates having different volumes are mixed to improve the biting property at the time of molding, shorten the molding cycle, and exhibit the inherent characteristics of the resin. The technical idea is that mechanical strength can be obtained. .

[0009]

Embodiments of the present invention will be described below. In the present invention, “weight” means “mass”. The average volume means a number average volume.

In the present invention, pellets are synonymous with chips and are resin particles. Usually, it has a length of 0.1 to 20 mm, and the shape is not particularly limited, but those having a columnar shape, a rectangular parallelepiped shape, a spherical shape, and a substantially spherical shape are generally used.

In the resin pellet mixture of the present invention, the resin pellet aggregate (a) and the resin pellet aggregate (b) are mixed, and the resin pellet aggregate (a) and the resin pellet aggregate (b) Ratio (a / b) 99.9 / 0.1-0.
1 / 99.1, preferably 99/1 to 1/99, more preferably 95/5 to 5/95. If the amount of the resin pellet aggregate (a) is large, the biting property is poor, and the tensile elongation is undesirably reduced. At least, it is not preferable because the biting property is poor and the tensile elongation is reduced.

The volume ratio (Va / Vb) of the resin pellet aggregate (a) having an average volume (Va) and the resin pellet aggregate (b) having an average volume (Vb) used in the present invention.
Is 1.01 to 10, preferably 1.02 to 5, and more preferably 1.03 to 3. If the volume ratio is less than 1.01, the biting property is significantly deteriorated, and if the volume ratio exceeds 10, the classification of the pellets proceeds, which is not preferable.

The standard deviation (S) of the observed volume of each of the resin pellet aggregate (a) and the resin pellet aggregate (b) used in the present invention is in the range of 0 ≦ S ≦ 2.0, and is preferably It is preferably from 0.01 to 1.5, more preferably from 0.05 to 1.0. If the standard deviation is more than 2.0, the biting property is remarkably reduced, which is not preferable.

The resin of the resin pellet used in the present invention is at least one resin selected from natural resins, semi-synthetic resins and synthetic resins, and may be any of a thermoplastic resin and a thermosetting resin. Among them, a thermoplastic resin is particularly preferable from the viewpoint of application to injection molding.

Examples of the thermoplastic resin used in the present invention include polyethylene, polypropylene, vinyl chloride, ABS resin, polyamide, polyester resin, polystyrene, polystyrene, polyacetal, polycarbonate, acrylic resin, polyester elastomer, and the like. Among them, a polyester resin is particularly preferable. Further, one or more kinds of other resins may be blended with polyester and used. Particularly, a polyester resin composition comprising a blend of a polyester and a modified or unmodified polyolefin is preferred.

The resin pellet aggregates (a) and (b) used in the present invention may be either resin pellets having the same composition or resin pellets having different compositions, but among them, resin pellets having different compositions are preferred. In addition, it is preferable that different types of compositions are used even when pellets other than the pellet aggregates (a) and (b) are contained.

The polyolefin preferably blended in the polyester resin composition is defined as a polymer of α-olefin such as propylene, butene-1, pentene-1, 4-methylpentene-1, octacene-1 and / or ethylene. It is a polymer having a structural unit. In particular, those containing ethylene as an essential component are preferable, and a polymer of this monomer and a copolymer with another monomer component can be used. Other monomer components include α-olefins such as propylene, butene-1, pentene-1, 4-methylpentene-1, octacene-1, and the like, such as random, block, and graft of one or more of these monomers to ethylene. Copolymers and mixtures are mentioned. Among these polyolefins, polyethylene and ethylene / polypropylene rubber are preferred. Particularly preferred are high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene and the like, and among them, high-density polyethylene is most preferred.

[0018] Of the modified or unmodified polyolefins, modified polyolefins are preferably used.
As the modifier, unsaturated carboxylic acids and / or derivatives thereof are preferable, and examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, isocrotonic acid, tetrahydrophthalic acid, citraconic acid, and butenedicarboxylic acid. Can be Examples of the unsaturated carboxylic acid derivative include an alkyl ester and an acid anhydride. Of these, acid anhydrides are preferable, and maleic anhydride is particularly preferably used. Two or more of these unsaturated carboxylic acids and derivatives thereof may be used in combination.

Usually, the polyolefin is modified by melt-mixing the unsaturated carboxylic acid and / or its derivative with the polyolefin and grafting the polyolefin. As a result, it acts to increase the compatibility with the polyester resin. For this purpose, at the time of melt-mixing, by using a radical generator such as an organic peroxide in an amount of 0.01 to 0.1% by weight based on the polyolefin, grafts can be formed more efficiently. As such a radical initiator, those having a molecular weight of 200 or more are particularly preferable. Specifically, t-butyl cumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butyl
Butylperoxy) hexane, 2,5-dimethyl-2,
5-di (t-butylperoxy) hexyne-3, α,
α'-di (t-butylperoxy) diisopropylbenzene and the like.

In the melt mixing, the compounding amount of the unsaturated carboxylic acid and / or its derivative is 0.1 to 20% by weight based on the polyolefin from the viewpoint of the effect of improving the mechanical strength and preventing the generation of insoluble matter by the crosslinking reaction. %, More preferably 0.5 to 10% by weight.

The polyester resin used in the present invention is a polymer or copolymer obtained by a condensation reaction containing dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative as main components, or a mixture thereof. is there. Among them, those having a butylene / terephthalate structural unit, an ethylene / terephthalate structural unit, a butylene / naphthalate structural unit, an ethylene / naphthalate structural unit and a cyclohexanedimethylene / terephthalate structural unit as main components are preferable, and the butylene / terephthalate structural unit is particularly preferable. preferable. A copolymerized polyester obtained by further copolymerizing a dicarboxylic acid and a diol as described below with these structural units may be used.

As the above dicarboxylic acid, isophthalic acid,
Phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-
Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, and 5-sodium sulfoisophthalic acid; adipic acid;
Examples include aliphatic dicarboxylic acids such as sebacic acid, azelaic acid and dodecanedioic acid, alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, and ester-forming derivatives thereof. The diol component has 2 to 2 carbon atoms.
An aliphatic glycol of 0, ie ethylene glycol,
Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,
6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, etc., or a long-chain glycol having a molecular weight of 400 to 6000, that is, polyethylene glycol, poly-1,3-
Examples include propylene glycol, polytetramethylene glycol, and the like, and ester-forming derivatives thereof.

Preferred examples of these polymers or copolymers include polybutylene terephthalate, polybutylene (terephthalate / isophthalate), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), and polybutylene (terephthalate / decanedicarboxylate). Rate), polybutylene naphthalate, polyethylene terephthalate, polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / 5-sodium sulfoisophthalate),
Examples thereof include polybutylene (terephthalate / 5-sodium sulfoisophthalate), polyethylene naphthalate, and polycyclohexane dimethylene terephthalate. Polybutylene terephthalate and polybutylene (terephthalate /
Adipate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate, polyethylene terephthalate, polyethylene (terephthalate / adipate), polyethylene naphthalate, polycyclohexane dimethylene terephthalate, and the like, most preferably polybutylene terephthalate It is.

These polyester resins have an intrinsic viscosity of 0.36 to 1.60 dl / g, particularly 0.52 to 1.35, when the o-chlorophenol solution is measured at 25 ° C.
Those in the range of dl / g are preferred from the viewpoint of mechanical properties and moldability. If the intrinsic viscosity is less than 0.36, the mechanical properties are poor, and if the intrinsic viscosity exceeds 1.60, the moldability tends to be poor.

The pellet mixture of the present invention is preferably a mixture of resin pellet aggregates having different compositions. It is preferable that at least one or more resin pellet aggregates contain the polyester resin composition. The following method is preferred as a method for producing a modified polyolefin comprising a polyolefin, an unsaturated carboxylic acid and / or a derivative thereof, and a polyester resin. That is, a polyolefin and an unsaturated carboxylic acid and / or a derivative thereof are first melt-mixed, mixed for a predetermined period of time, then further added with a polyester resin in a molten state, and melt-mixed. Pelletize into pellets. Such a method is preferably used because a polyolefin modified with an unsaturated carboxylic acid and / or a derivative thereof can be dispersed in a thermoplastic polyester in a suitable size, and when the polyester is partially substituted with an unsaturated carboxylic acid. And / or being modified by a derivative thereof is considered as an effect.

As a specific method of such melt mixing, a twin screw extruder having two input ports is used, and polyolefin and unsaturated carboxylic acid and / or a derivative thereof are introduced through a main input port installed at the screw root side. And a method of supplying and melt-mixing the polyester resin from a sub-inlet installed between the main inlet and the extruder tip, or a polyolefin and an unsaturated carboxylic acid and / or a A method in which the derivative is melt-mixed, and a polyester resin is charged after a predetermined time has elapsed.
Specifically, the time from the start of melting and mixing the polyolefin and the unsaturated carboxylic acid and / or its derivative until the addition of the polyester resin is 5 seconds or more, preferably 10 seconds or more, and 300 seconds or less, and more preferably 200 seconds or less. Seconds or less are preferred. If added in a short time, the toughness of the resulting polyester resin composition tends to deteriorate, and if mixed long, the molding fluidity of the resin composition tends to deteriorate.

When a polyester resin and a polyolefin are blended in the resin pellet mixture of the present invention, the value of polyolefin / (polyester resin + polyolefin) is preferably 0.1 to 50% by weight, more preferably 5 to 50%. It is preferably 40%, and more preferably 10 to 40%. If the proportion of the polyolefin is small, the effect of modifying the polyolefin cannot be obtained, and if it is too large, the properties of the polyester tend to be lost. On the other hand, if the ratio of the polyolefin to the polyester is too small or too large, the compatibility between the polyester and the polyolefin tends to decrease, and the mechanical strength tends to decrease.

In the resin pellet mixture of the present invention, a low crystalline polyester resin can be blended in addition to polybutylene terephthalate. The use of this low-crystalline polyester is preferable because the molding shrinkage when the obtained mixture is molded becomes small and distortion is less likely to occur in a molded product. Examples of the low crystalline polyester resin include polybutylene (terephthalate / isophthalate), polybutylene (terephthalate / isophthalate), polyethylene terephthalate, polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), bisphenol A (terephthalate / Isophthalate), polybutylene (terephthalate / naphthalate), polyethylene naphthalate,
Polycyclohexane dimethylene terephthalate, polycyclohexane dimethylene (terephthalate / isophthalate), poly (cyclohexane dimethylene / ethylene)
Examples include terephthalate and poly (cyclohexane dimethylene / ethylene) (terephthalate / isophthalate). Among them, poly (cyclohexane dimethylene / ethylene) terephthalate is preferably used in view of moldability, fluidity, and mechanical properties of the polyester resin composition, particularly impact resistance and heat resistance.

Particularly, the molar ratio between the cyclohexanedimethanol component and the ethylene glycol component is 50/50 to 80/2.
Poly (cyclohexane dimethylene / ethylene) terephthalate of 0 is preferably used. When a low-crystalline polyester resin is blended as described above, the amount is preferably 1 to 50% by weight, more preferably 5 to 30% by weight in the resin pellet mixture.

The low-crystalline polyester has an intrinsic viscosity of 0.3 when its o-chlorophenol solution is measured at 25 ° C.
Those having a range of 36 to 1.55 dl / g, particularly 0.52 to 1.25 dl / g are suitable from the viewpoint of mechanical properties and moldability. If the intrinsic viscosity is low, mechanical properties tend to be poor, and if the intrinsic viscosity exceeds 1.55, moldability tends to be poor. The resin may be blended with any of the resin pellets.

The pellet mixture of the present invention can further contain various other additives. As these additives, for example, glass fiber, carbon fiber, asbestos fiber, rock wool, calcium carbonate, silica sand, bentonite, kaolin, talc, clay, wollastenite,
Reinforcing agents such as barium sulfate, glass beads, mica, etc., fillers, nucleating agents or antioxidants (phosphorous, sulfuric, etc.), UV absorbers, heat stabilizers (hindered phenolic, etc.), lubricants, mold release Agents, colorants including dyes and pigments, flame retardants (halogen-based, phosphorus-based, etc.), flame-retardant aids (antimony compounds represented by antimony trioxide, zirconium oxide, molybdenum oxide, etc.), foaming agents, crosslinking agents ( For example, polyvalent epoxy compounds, isocyanate compounds, acid anhydrides, and the like) can be mentioned. These additives may be blended in any resin pellet.

The resin pellet mixture of the present invention can be formed into a desired molded product by any molding method such as injection molding, extrusion molding, blow molding, vacuum molding, etc., and is suitable for injection molding due to its characteristics. Applications include automotive parts, electric and electronic parts, especially plugs, coil bobbins, sockets, switches, tuner parts, relays, capacitors, terminal boards, valves, fuse cases, flyback transformer cases, connectors, brush holders for motors, and lamps. It is useful for applications requiring high cycle characteristics and thin-walled mechanical properties, such as sockets, rear end panels, distributor caps, ignition coils, fuel pumps, transmission valves, carburetor parts, and especially connectors for automobile parts.

[0033]

EXAMPLES The effects of the present invention will be further described below with reference to examples.

Production of polyester resin composition (A) Reference Example 1 Production of polyester resin pellet aggregate (A
-1, A-2, A-3, A-4) Polybutylene terephthalate having an intrinsic viscosity of 0.9 was melt-mixed to adjust the discharge amount and take-up speed, and extruded and pelletized, and averaged as shown in Table 1. An aggregate of resin pellets having a volume was manufactured.

The extruder was a 30 mm twin screw extruder with L / D = 35, and the cylinder temperature was set to 250 ° C.

Reference Example 2 Production of polyester resin composition pellet aggregate (B-1) High density polyethylene (hereinafter referred to as HDPE) having a specific gravity of 0.97 and a melt flow rate at 190 ° C. of 5.2 g / 10 min.
), Maleic anhydride (hereinafter referred to as MAH) as an unsaturated carboxylic acid and / or a derivative thereof, a radical initiator (2,5-dimethyl-2,5-di (t-butylperoxy) hexane: trade name perhexa2) .5B (manufactured by NOF CORPORATION) (hereinafter referred to as PH25B) were mixed in the proportions shown in Table 1 and supplied from the main feed port of an extruder. Polybutylene terephthalate having an intrinsic viscosity of 0.9 (hereinafter referred to as PB) was used.
(Abbreviated as T) from a side feeder and melt-mixed, and then pelletized to produce a polyester resin composition having an average volume shown in Table 1.

The extruder used was a 30 mm twin-screw extruder with L / D = 35, and the cylinder temperature was set at 230 ° C. from the main supply port to the side feeder, and thereafter at 260 ° C.

[0038]

[Table 1]

Examples 1 to 8 Comparative Examples 1 to 8 One or two types of pellet aggregates were selected from the pellet aggregates produced in the reference example, and mixed in a V-type blender at a ratio shown in Table 2 to produce a resin pellet mixture. An ASTM No. 4 dumbbell test piece having a thickness of 1 mm was formed from the resin pellet mixture at a mold temperature of 40 ° C. by using a screw in-line injection molding machine having a mold temperature of 270 ° C. and a clamping pressure of 50 t. The biting time and the molding cycle during the molding were measured together.

Further, the ASTM No. 4 dumbbell test piece that had been injection-molded was subjected to high-speed tensile tests at 500 mm / sec and 1000 mm / sec to evaluate mechanical properties. Table 2 shows the results. Table 3 shows a comparative example.

[0041]

[Table 2]

[0042]

[Table 3]

From the results of Tables 2 and 3, the pellet mixture having the characteristics of the present invention has a very high molding bite speed and shortens the molding cycle, while the molded product obtained is thin and has excellent mechanical properties.

[0044]

By using the pellet mixture of the present invention, the average biting time during injection molding and the moldability represented by the molding cycle are excellent, and the mechanical properties represented by the high elongation by the high-speed tensile test are excellent. A molded article having excellent physical properties can be obtained.

Claims (12)

[Claims] 1. A mixture of resin pellets having different average volumes, wherein the resin pellet aggregate (a) having the largest average volume (Va) and the resin pellet aggregate (b) having the smallest average volume are formed. Average volume (Vb) ratio (Va
/ Vb) is a resin pellet mixture of 1.01 to 10.0. 2. The weight ratio (a / b) of the resin pellet aggregate (a) to the resin pellet aggregate (b) is 99.9 / 0.1.
The resin pellet mixture according to claim 1, wherein the mixture has a relationship of 0.1 to 99.9. 3. The resin pellet mixture according to claim 1, which is used for injection molding. 4. The resin pellet mixture according to claim 1, wherein at least one of the resin pellets contains a polyester resin or a polyester resin composition. 5. The resin pellet mixture according to claim 4, wherein the resin pellet contains a polyester resin composition, and the polyester resin composition is a mixture of a polyester resin and another resin. 6. The resin pellet mixture according to claim 5, wherein the other resin is a modified or unmodified polyolefin. 7. A large resin pellet aggregate (a) (average volume is defined as Va) and a small resin pellet aggregate (b).
(An average volume is defined as Vb). (However, Va / Vb
Is 1.01 to 10.0. ) 8. The weight ratio (a / b) of the resin pellet aggregate (a) to the resin pellet aggregate (b) is 99.9 / 0.1.
The method for producing a resin pellet mixture according to claim 7, which has a relationship of 0.1 to 99.1. 9. The method for producing a resin pellet mixture according to claim 7, wherein at least one of the resin pellet aggregates contains a polyester resin or a polyester resin composition. 10. The method for producing a resin pellet mixture according to claim 8, wherein the resin pellet aggregate contains a polyester resin composition, and the polyester resin composition is a mixture of a polyester resin and another resin. 11. The method for producing a resin pellet mixture according to claim 17, wherein the other resin is a modified or unmodified polyolefin. 12. A method for producing a resin pellet aggregate (a) or (b), wherein a polyolefin and an unsaturated carboxylic acid and / or a derivative thereof are melt-mixed, and then the molten state is further maintained. The method for producing a pellet mixture according to claim 11, wherein the polyester resin is melt-mixed and then pelletized.