JP2009083412A - Sandwich molding applying diffusion of additive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sandwich molding showing excellent moldability made by compounding a necessary amount of a functional additive in a synthetic resin material or a sandwich molding showing excellent moldability made by compounding a different functional additive. <P>SOLUTION: The sandwich molding is made by not compounding the functional additive in a skin layer resin material but compounding a major functional additive in a core layer resin material or by compounding a sub-functional additive in a skin layer resin material and compounding the major functional additive in the core layer resin material; by being sandwich-molded; and then by being heated at a temperature not lower than a glass transition temperature of the synthetic resin material to make the major functional additive compounded in the core layer resin material bleed out on the surface of the skin layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sandwich molded article containing a functional additive and having excellent moldability.

  Functionality such as lubricants, antistatic agents, and flame retardants in the synthetic resin materials that make up the synthetic molded product when adding value such as sliding properties, antistatic properties, and flame retardancy to the synthetic resin molded product An additive is blended (see Patent Document 1). In that case, it is desirable to add a large amount of the additive from the viewpoint of performance and sustainability of performance.

  However, some functional additives may deteriorate the moldability of the synthetic resin material in the molding process and cause poor appearance, or the additive bleed out on the surface of the synthetic resin material may adhere to the mold and cause contamination. Therefore, there is a problem that the blending amount of the additive must be determined not from the viewpoint of performance or the sustainability of the performance but from a viewpoint different from the original purpose such as moldability.

  Furthermore, when a plurality of additives having different functions are blended, if the compatibility between the additives is not taken into account, the moldability is deteriorated or the strength of the molded product is significantly reduced. There was a problem that the amount and combination of functional additives were limited.

On the other hand, as a functionalization by a molding method, sandwich molding in which materials of the surface layer (skin layer) and the inside (core layer) are changed is known as a co-injection molding method using a multicolor molding machine.
This molding method has the advantage of higher functionality than products made of ordinary single materials. For example, new materials are used as skin layers and recycled materials are used as core materials for the purpose of environmental conservation through the use of waste plastics. Sandwich molded product used for the layer (see Patent Document 2), sandwich molded product using a general material for the skin layer and a foaming agent compounded material for the core layer for the purpose of improving dimensional accuracy (see Patent Document 3), and the other party Sandwich molded products using a general material for the skin layer and a fiber reinforced material for the core layer (see Patent Document 4) and the like are known for the purpose of achieving both aggression (sliding) relaxation to the material and high rigidity.

When using such a sandwich molding method to improve the functionality of plastic molded products by adding functional additives, use a general material for the core layer and a material containing the functional additive for the skin layer. It is common to do.
According to this method, the amount of the functional additive can be reduced, but the deterioration of moldability due to the functional additive cannot be completely solved. Still remained.
JP 2000-72214 A JP 2001-225351 A JP 2000-33635 A (paragraph number [0046] in the specification) JP 2004-125139 A

The present invention solves the above-described problems. That is, the object of the present invention is to provide a sandwich molded product having a required amount of a functional additive in a synthetic resin material and having excellent moldability. Is to provide.
Another object of the present invention is to provide a sandwich molded product having different functional additives and excellent moldability.

  As a result of repeated research on the molding method of the synthetic resin, the present inventors can use the synthetic resin containing the functional additive for the core layer to make the appearance good with the general material of the skin layer, In addition, the functional additive in the synthetic resin is present in the amorphous part of the synthetic resin, and when the glass transition temperature (Tg) is exceeded, the functional additive is extruded to the surface layer (bleed out) by the molecular motion of the amorphous part. Invented.

That is, the aspect of this invention is as follows.
(1) A sandwich molded product obtained by sandwiching a skin layer resin material with a functional additive-free resin and blending a core layer resin material with a main functional additive.
(2) A sandwich molded product comprising a skin layer resin material blended with a sub-functional additive and a core layer resin material blended with a main functional additive and sandwiched.
(3) After sandwich molding, heat treatment is performed at a temperature equal to or higher than the glass transition temperature of the synthetic resin material, and the main functional additive blended in the core layer resin material is bleeded out to the skin layer surface (1 ) Or (2) sandwich molded article.
(4) The sandwich molded article according to (3), wherein the heat treatment uses a high temperature generated when the sandwich molded article is used.

According to the present invention, the skin layer is not compounded with a functional additive that adversely affects moldability during sandwich molding, or only a stable additive that does not adversely affect moldability. It is possible to obtain a sandwich molded article having an excellent appearance by suppressing deterioration in properties and a significant decrease in strength. After that, if the sandwich molded article is heated to a temperature exceeding Tg, the functional additive present in the core layer can be obtained. Bleed out on the surface of the skin layer, and the desired function can be expressed in the sandwich molded product.
Further, according to the present invention, since the additive is blended in the core layer that does not affect the appearance of the sandwich molded product, a high concentration can be blended, and the effect of the additive can be maintained for a long time.

  Furthermore, since a plurality of incompatible additives that adversely affect the appearance and strength are blended separately into the skin layer and the core layer, two or more optional additives can be easily blended for different purposes. After that, if the sandwich molded product is heated to a temperature exceeding Tg, other functional additives existing in the core layer bleed out to the surface of the skin layer, and multiple functions are exhibited in the sandwich molded product. Can be made.

  Specific embodiments of the sandwich molded product according to the present invention include plastic chains and chain guides in the conveyance field, cables for moving and guiding tensioner levers, cables and hoses in timing systems in the vehicle engine field. There is a cable protection guide device called Bear (registered trademark).

The main functional additive as used in the present invention is blended with a resin material in order to develop added values such as sliding properties, antistatic properties, flame retardancy, antibacterial / antifungal properties, etc. in plastic molded products. is there. Deteriorating resin moldability, for example, lubricants such as hydrocarbon lubricants, fatty acid lubricants, fatty acid amide lubricants, ester lubricants, cationic activators, anionic activators, amphoteric activators, etc. Anti-static agents, chlorine-based flame retardants, bromine-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, and other anti-bacterial agents such as organic anti-bacterial and anti-fungal agents, inorganic anti-bacterial and anti-fungal agents Even if it is an antifungal agent, it can be used without any problem since it is incorporated in the core layer not directly involved in molding.
Further, the sub-functional additive as used in the present invention is an additive different from the main functional additive and does not adversely affect the moldability even if it is blended alone in the synthetic resin material.
When combined with the main functional additive, there is no problem because it is separated from the main functional additive at the time of sandwich molding, even if it may adversely affect the moldability or reduce the strength. Can be used.

Examples of combinations of functional additives that have previously been considered unfavorable for use in combination according to the present invention include the following.
(1) A solid lubricant such as PTFE, carbon, molybdenum disulfide, or silicone polymer is added to the skin layer as a secondary functional additive, and a semi-solid such as olefin wax or fatty acid ester is used as the main functional additive in the core layer. Or a sandwich molded product with a combination of liquid lubricants that can maintain high sliding characteristics for a long period of time under any of the conditions of “low surface pressure / high speed” and “high surface pressure / low speed”.
(2) A sandwich molded product in which a sliding additive is blended in the skin layer and a surfactant antistatic agent is blended in the core layer to have both sliding characteristics and antistatic performance.
(3) A sandwich molded product in which a conductive polymer is blended in the skin layer, a semi-solid or liquid lubricant is blended in the core layer, and both sliding characteristics and antistatic performance are combined.

  The “heat treatment” referred to in the present invention needs to be performed at a temperature equal to or higher than Tg of the synthetic resin material and lower than the melting temperature, but a temperature range of about Tg to Tg + 2 to 3 ° C. is preferable. And this heat processing may be a heat processing after sandwich molding, and may utilize the high temperature which generate | occur | produces when using a sandwich molded product.

  The heat treatment of the present invention needs to be performed for a time sufficient for the seed functional additive blended in the core layer to bleed out to the surface of the skin layer.

Thus, in this invention, the functional additive mix | blended in the synthetic resin material can be bleed out to the skin layer surface by heat-processing at the temperature of Tg vicinity after sandwich molding.
Further, in the present invention, it may be possible to bleed out to the surface of the skin layer by utilizing a high temperature generated when using a sandwich molded product. For example, sliding of a plastic chain, a chain guide, etc. in the conveying field If it is a part, diffusion can be achieved even with sliding heat during use and the expected function can be expressed, and if it is a part used in a burning atmosphere such as a tensioner lever in a timing system in the vehicle engine field, Since the diffusion proceeds and the intended function can be developed even when the heating is in use, the prior heat treatment can be omitted.

The synthetic resin material used in the present invention may be of any type as long as it is a synthetic resin material that can be injection-molded. However, in consideration of recyclability, it is desirable that the skin layer and the core layer be of the same type.
In addition, as described above, the functional additive exists in the amorphous part of the synthetic resin and diffuses to the surface through the amorphous part. It is desirable that the crystallinity of the resin is not too high, specifically 80% or less.
Further, since such diffusion proceeds by the Brownian motion of the amorphous part, it is desirable that the glass transition temperature is not too high. Specifically, Tg = 80 ° C. or less is desirable.

  Considering the above, the synthetic resin material used in the present invention is preferably polyethylene (PE), polypropylene (PP), polyamide (PA), polyacetal (POM), polyethylene terephthalate (PET), but is not limited thereto. It is not done.

In order to facilitate the diffusion of the functional additive compounded in the core layer, the thickness of the skin layer is desirably thin, specifically 1 mm or less.
In order to form such a thin skin layer, it is desirable that the viscosity of the synthetic resin material of the core layer is higher than the viscosity of the synthetic resin material of the skin layer.
Furthermore, since the functional additive compounded in the core layer passes through the amorphous part of the synthetic resin and diffuses to the surface, it is desirable that the molecular weight is not too large.

(1) PP-ester additive calibration curve An IR chart obtained by surface analysis of a sandwich molded product obtained by sandwiching 3 wt% of an ester additive with polypropylene (PP) by FT-IR It is shown in 1.
Here, the absorbance ratio (intensity ratio) of 1460 cm-1 [C-CH3 bending vibration, -CH2 bending vibration] peculiar to PP and 1745 cm-1 [C = O stretching vibration] peculiar to ester additives is used as an additive. Concentration parameter.
The absorbance ratio (y) when the concentration (x) of the ester-based additive was 1, 2, 3 wt% was determined, and a calibration curve was determined on the assumption of linear regression passing through the origin. As shown in FIG. = 0.249x was obtained.

(2) Confirmation of diffusion (bleed out) of functional additive Next, the core layer is polypropylene (PP) +3 wt% ester-based additive, and the skin layer is “polypropylene (PP) -additive-free formulation” and “polypropylene ( Two types of sandwich molded products (PP) + silicone-based sliding additive (additive that is stable to resin moldability) 3 wt% "are prepared, and heat treatment (60 ° C x 24Hr, 60 ° C x 48Hr) is performed. Then, surface analysis was performed by FT-IR, and when bleedout occurred, the concentration of the ester-based additive from the calibration curve obtained in Example 1, that is, the estimated surface concentration (wt%) in the skin layer 3 and FIG. 4 show the results. It has been confirmed that the waveform of polypropylene (PP) alone does not change even when heat treatment is performed.
As is apparent from the results of FIGS. 3 and 4, the main functional additive consisting of an ester-based additive compounded in the core layer by sandwich molding is a secondary functional additive consisting of another functional additive in the skin layer. It was confirmed that bleed out regardless of whether or not was added.

FIG. 5 and FIG. 6 show the relationship between the estimated surface concentration of the above measured value in the skin layer and the heat treatment time.
It can be seen that when the amount of the silicone-based additive is 5 wt% or more, the estimated surface concentration in the skin layer and the heat treatment time are in a proportional relationship.
Moreover, when the silicone-based additive was contained in the skin layer, the start-up at a low concentration of 1 to 3 wt% was quicker.
Further, in the heat treatment of 24 Hr, the bleed out amount was larger than “without silicone” at 1 to 3 wt%, but the bleed out amount was smaller in the heat treatment of 48 Hr than “no silicone” except for 1 wt%.

  ADVANTAGE OF THE INVENTION According to this invention, the sandwich molded product provided with arbitrary functions can be manufactured without a molding defect and intensity | strength deterioration, and it is industrially advantageous.

The figure which shows IR chart of a polypropylene +3 wt% ester type additive. The figure which shows the calibration curve calculated | required from the density | concentration (x) of an ester type additive, and the light absorbency ratio (y). The figure explaining the surface estimated density | concentration of the sandwich molded product heat-processed for 24 hours. The figure explaining the surface estimated density | concentration of the sandwich molded product heat-processed for 48 hours. The figure explaining the estimated surface density | concentration of the sandwich molded product of a silicone additive-free skin layer. The figure explaining the estimated surface density | concentration of the sandwich molded product of a silicone addition skin layer.

Claims (4)

  A sandwich molded product characterized in that the skin layer resin material is a resin with no functional additive added, and the core layer resin material is blended with the main functional additive and sandwich molded.   A sandwich molded product comprising a skin layer resin material containing a secondary functional additive and a core layer resin material containing a main functional additive, and sandwich molding.   The main functional additive blended in the core layer resin material is bleeded out to the surface of the skin layer after the sandwich molding and heat treatment at a temperature equal to or higher than the glass transition point of the resin material. The sandwich molded article according to claim 2.   4. The sandwich molded article according to claim 3, wherein the heat treatment uses a high temperature generated when the sandwich molded article is used.

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