JPH08283422A - Molding of pet resin and additive-containing resin pellet therefor - Google Patents

Abstract

PURPOSE: To obtain a stable molded product uniform in both wall thickness and shade, useful as e.g. a container, by using a mixed resin containing additive- contg. resin pellets as feedstock to suppress crystallization due to the crystal- nucleating action of the additive. CONSTITUTION: (A) An additive-contg. resin pellets suppressed in the rate of crystallization are prepared in advance by incorporating (i) a noncrystalline resin or (ii) a resin lower in the rate of crystallization than polyethylene terephthalate resin (hereinafter, abbreviated to PET) or (iii) a resin composition with these resins as the chief raw material with (iv) additive particles. The component A is then blended with (B) PET resin to obtain a mixed resin which is used as feedstock. It is preferable that the surface of the component (iv) be coated with the component (i) (esp. a PET copolymer) or component (ii) or component (iii) and the resultant coated component (iv) be incorporated in the component B to prepare the feedstock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a PET resin containing additives such as antistatic agents and pigments.

[0002]

2. Description of the Related Art PET resin (polyethylene terephthalate) is used in various containers because it has high rigidity, high gloss, high heat resistance, is lightweight, has excellent water vapor barrier properties, and is beautiful. Oral-related products such as mouthwash, liquid toothpaste, hair care products such as shampoos and conditioners, household products such as detergents, beverages, pharmaceuticals, etc., and their usage ranges are wide. Such a PET resin container is manufactured by a blow molding method or an injection molding method, but when the container is a bottle, a stretch blow molding method is particularly used.

[0003]

Usually, if a PET resin alone (hereinafter referred to as "homogen PET") shows good moldability in stretch blow molding, additives such as antistatic agents and pigments are usually used. When is added, a phenomenon that the moldability is lowered occurs. This is also caused by a decrease in the temperature of the parison and a decrease in the melt viscosity due to the addition of additives, but the largest cause is the crystallization phenomenon of the PET resin. That is, PET
Since the resin originally has the property of easily crystallizing, PE
When additives such as antistatic agents and pigments are added to T resin,
Crystallization of the PET resin is promoted by the crystal nucleating property of the additive, and as a result, a phenomenon of deterioration in moldability occurs. The degree of decrease in moldability depends on the amount of the additive compounded, but in general, when the additive is compounded to the extent that its effect is exhibited, the parison does not swell even if air is blown, or the finished product There are many troubles such as uneven thickness, and extremely thin wall part. For example, when an antistatic agent is taken as an example, blow molding becomes difficult when the weight percentage is 2.0% or more. The present invention has been made in view of the present situation, and a PET resin containing an additive such as an antistatic agent or a pigment is unevenly swollen,
It is an object of the present invention to provide a molding method capable of stably molding without causing deformation or uneven thickness.

[0004]

One of the methods for solving the above problems is to add a substance that suppresses the crystal nucleation effect of the additive to the whole PET resin after the additive is added. Can be considered. However, since such a material is much more expensive than PET resin,
The above method, which requires a large amount of such materials, has poor industrial applicability. The present inventor has obtained the following idea as a result of studying a molding method suitable for industrial use because the required amount of the substance that suppresses the crystal nucleation action is small. That is, the target to be subjected to the treatment for suppressing the crystal nucleation effect by the additive is not the entire PET resin, but only the additive-containing resin pellets added to the PET resin in the first stage of the molding process. Was conceived. Then, even if the target of the treatment for suppressing the crystal nucleation effect by the additive is limited to the additive-containing resin pellets as described above, the effect of suppressing the crystal nucleation effect substantially extends to the entire PET resin. The present invention has been completed by confirming the above. The present invention completed based on such an idea has the following contents.

The invention according to claim 1 is an amorphous resin or P
An additive-containing resin pellet in which additive particles are filled in a resin having a slower crystallization rate than ET resin or a resin composition containing these resins as a main raw material to suppress the crystallization rate is prepared in advance It is characterized in that the resin pellets are molded by using a mixed resin obtained by mixing the resin pellets with a PET resin which is a resin that is easily crystallized.

According to the second aspect of the present invention, the resin filled with the additive particles is not required to have a function of suppressing the crystal nucleation action, but instead the individual additive particles are provided with a resin having a crystal nucleation action suppressing effect. It is characterized by being coated with.

According to a third aspect of the present invention, individual additive particles are coated with a resin having a crystal nucleation suppressing effect, and the coated additive particles are further coated with a resin having a crystal nucleating suppressing effect. It is characterized by being filled inside.

A PET copolymer can be used as the amorphous resin. As the copolymer component of the PET copolymer, for example, dibasic acid or dihydric alcohol is suitable.

A resin pellet for use in the molding method according to claims 1 to 3 is proposed as follows. Corresponding to the molding method of claim 1, an additive having a crystal nucleating property such as a pigment or an antistatic agent in an amorphous resin or a resin having a slow crystallization rate or a resin composition containing these resins as a main raw material. Additive-containing resin pellets filled with are proposed.

According to the molding method of claim 2, the surface of the additive particles having a crystal nucleating property such as a pigment and an antistatic agent may be a resin having a slower crystallization rate than an amorphous resin or a PET resin. Is coated with a resin composition containing these resins as main raw materials, and the coated additive particles are treated with PE.
Additive-containing resin pellets filled in T resin are proposed.

According to the molding method of claim 3, the surface of the additive particles having a crystal nucleating property such as a pigment, an antistatic agent, or the like has a slower crystallization rate than an amorphous resin or a PET resin. A resin composition in which these resins are coated with a resin composition which is a main raw material, and the coating additive particles have a slower crystallization rate than an amorphous resin or a PET resin, or a resin composition which uses these resins as a main raw material resin Additive-containing resin pellets filled in are proposed.

[0012]

The additive in the additive-containing resin pellet is surrounded by the resin having a lower crystallization rate than the amorphous resin or the PET resin. In each of claim 1, claim 2 and claim 3, the surrounding form is different, but in each case the amorphous resin or the resin having a slower crystallization rate than the PET resin adheres closely to the surface of the additive. It is common in that the additives are kept out of contact with the PET resin. Molding process of PET resin In the first step, the additive-containing resin pellets are mixed with the PET resin, but even after being mixed in the PET resin, the amorphous resin or the resin having a slow crystallization rate is surrounded by the additive particles. Keep encircling. Then, the additive particles are prevented from coming into contact with the PET resin to prevent the additive particles from exhibiting the crystal nucleating property with respect to the PET resin. When the surface of the additive particles is directly coated with an amorphous resin or a resin having a slow crystallization rate as in claims 2 and 3, this coating prevents contact with the PET resin, while In the case where the additive particles are filled in the amorphous resin or the resin having a slow crystallization rate as described in 1, the amorphous resin or the crystallization occurs around the additive particles even after mixing with the PET resin. The uneven distribution of the low-speed resin in a concentrated manner suppresses contact with the PET resin.

In the molding method of the present invention, the additive particles, which are the crystallization promoting factors of the PET resin, are directly surrounded by the amorphous resin or the resin having a slow crystallization rate so as to prevent the contact with the PET resin, or Since the amorphous resin or the resin having a slow crystallization rate is concentrated and unevenly distributed around the additive particles to suppress contact with the PET resin, the crystallization suppressing effect is extremely high, and the amorphous resin is also amorphous. A small amount of the organic resin or the resin having a slow crystallization rate is sufficient.

[0014]

Embodiments of the present invention will be described below. When imparting an antistatic effect to the PET resin or coloring it, additive-containing resin pellets containing additives such as an antistatic agent and a pigment in the first stage of the molding process (hereinafter,
It is common practice to mix a so-called masterbatch) into PET resin. In the conventional master batch, the same PET resin as the PET resin to be mixed is used as a base resin, and additives such as an antistatic agent and a pigment are uniformly dispersed in this base resin. In the present invention, the crystallization speed of the masterbatch is suppressed to suppress the crystallization speed of the entire PET resin mixed with the masterbatch. The masterbatch proposed by the present invention includes: A) an amorphous resin or a resin 2 having a slow crystallization rate (hereinafter, both the amorphous resin and the resin having a slow crystallization rate are generically referred to as a crystal nucleation-inhibiting resin 2) is filled with additive particles 1. (FIG. 1) B) A masterbatch B in which the surface of the additive particles 1 is coated with a crystal nucleation action suppressing resin 2a and the coating additive particles 1 are filled in a PET resin 10a.
(FIG. 2) C) A masterbatch C in which the surface of the additive particle 1 is coated with the crystal nucleation suppressing resin 2a, and the coated additive particles 1 are further filled in the crystal nucleation suppressing resin 2. (Fig. 3) can be considered. The molding method of the present invention is realized by kneading such a masterbatch with the PET resin 10, which is the main component, in the first stage of the molding process.

The state of the PET resin before and after kneading in the case of using the masterbatch A is shown in the schematic diagram of FIG. The additive particles 1 filled in the crystal nucleation suppressing resin 2 are P
By being kneaded with the ET resin 10, the PET resin 10
Although dispersed therein, the additive particles 1 are dispersed in the PET resin 10 along with the crystal nucleation action suppressing resin 2 around the additive particles 1. Therefore, the additive particles 1 accompanied by the crystal nucleation suppressing resin 2 are uniformly dispersed in the PET resin 10 after kneading, and the antistatic effect is imparted to the entire PET resin 10, or The entire resin 10 may be colored uniformly. Then, since the periphery of the additive particle 1 is surrounded by the crystal nucleation effect suppressing resin 2 and the contact with the PET resin 10 is cut off, the additive particle 1 does not become a crystal nucleus. Since the masterbatch A is prepared by only kneading the additive particles 1 into the crystal nucleation action suppressing resin 2, the preparation cost of the masterbatch A is relatively low.

The state of the PET resin before and after kneading in the case of using the masterbatch B is shown in the schematic view of FIG. In this case, since the surface of each additive particle 1 is completely covered with the crystal nucleation suppressing resin 2a, the contact between the additive particle 1 and the PET resin 10 after kneading is more completely cut off.

Further, the state of the PET resin before and after kneading when using Masterbatch C is shown in the schematic diagram of FIG. In this case, the surface of each of the additive particles 1 is coated with the crystal nucleation inhibitory resin 2a, and the additive particles 1 subjected to the coating treatment are further coated with the crystal nucleation inhibitory resin 2 which is a base resin.
Since it is filled inside, the additive particles 1 and the PET resin 10 after the kneading are doubly blocked, and the crystallization suppressing function becomes more excellent.

As the crystal nucleation action suppressing resin 2, not only an amorphous resin but also a resin having a slower crystallization rate than a PET resin is applicable. Examples of such a resin include PET-G resin and the like. In addition, the crystal nucleation suppressing resin 2 is PE
It goes without saying that a resin having excellent compatibility with the T resin 10 is used.

As the amorphous resin, for example, a PET copolymer can be used, and as the copolymer component of the PET copolymer, a dibasic acid such as isophthalic acid or a dihydric alcohol such as cyclohexanedimethanol can be mentioned.

The content of the additive particles 1 varies depending on the expected effect, efficacy, type of the crystal nucleation suppressing resin 2, and the form of the masterbatch. For example, the additive particles 1
Is an antistatic agent or a pigment, the crystal nucleation effect suppressing resin 2 is a PET copolymer, and the masterbatch is a type in which the PET particles are filled with the additive particles 1, and the resin composition after kneading The additive concentration is 1.0% by weight or more, and is 1.0% by weight in reality.
Is in the range of up to 4.0% by weight.

For mixing the masterbatch with homo PET, a general-purpose mixing device such as a tumbler, a V blender or a Henschel mixer can be used, and the temperature environment during mixing is sufficient at room temperature.

The coating operation of the individual additive particles 1 with the PET copolymer is carried out by melt-extrusion after adding a titanium coupling agent or a silane coupling agent to the pigment to cause a reaction, re-grinding and then mixing with the PET copolymer. You can

When an amorphous resin is used as the crystal nucleation suppressing resin 2, the ratio of the amorphous resin in the obtained molded product can be extremely reduced, and the amount thereof is 1.0 weight of the total weight of the molded product. % To 10.0% by weight.

The method of the present invention is effective in both the stretch blow molding method and the injection molding, but the effect in the stretch blow molding method is particularly remarkable.

Next, a comparative test conducted to confirm the effect of the present invention will be described. As an example of the present invention, the one by the molding method shown in claim 1 was taken up. The components used in the examples are as follows. Antistatic Agent Atrai (Nippon Mineral Co., Ltd.) PET-G J240 (Copolymer 10% by weight Mitsui Pet Co., Ltd.) PET-G JA125 (Copolymer 2% by weight Mitsui Pet Co., Ltd.) Homo PET J120 (Mitsui Pet Co., Ltd.) <Example 1> First, PET-G. J240 was crushed, 20 wt% of atrai was added and mixed, and then melt-extruded to obtain a pellet-shaped master batch. Next, homo PET. J1
The master batch was mixed with 20 pellets at a ratio of 5, 10 and 20% by weight to obtain three kinds of mixed resins having different mixing ratios of the master batch. The pellets were mixed with each other at room temperature using a Henschel mixer. Put the mixed resin into a stretch blow molding machine, and under the molding conditions compatible with PET resin, resin injection, parison molding → parison release, preheating → blow molding → taking out the molding bottle. Stretch blow molding was performed along. PET in mixed resin. J120 having a compounding amount of 5% by weight is "Example 1-1", 10% by weight of "Example 1-2", and 20% by weight of "Example 1-".
3 "was evaluated for antistatic effect, uniform and stable blowing property, and uniformity of wall thickness. The results are shown in Table 1. <Example 2> Next, PE of the masterbatch pace resin was used.
TG. Instead of JA125, stretch blow molding similar to the above was performed and evaluated. The results are shown in Table 1. Example 3 First, a titanium coupling agent was added to titanium oxide (pigment) to react the coupling agent with the pigment, and then,
Re-grind. Then PET-G. After crushing J240 and adding 50% by weight of titanium oxide subjected to coupling treatment and mixing, melt extrusion was carried out to obtain a pellet-shaped master batch. Next, homo PET. The master batch was mixed with the pellets of J120 at a ratio of 5, 10 and 20% by weight, respectively, to obtain three kinds of mixed resins having different mixing ratios of the master batch. The pellets were mixed with each other at room temperature using a Henschel mixer. Thereafter, in the same manner as in Example 1, the mixed resin was put into a stretch blow molding machine, and resin injection and parison molding were performed under molding conditions compatible with the PET resin.
Stretch blow molding was carried out in accordance with the work procedure of parison release, preheating → blow molding → removal of molded bottle. PET in mixed resin. A blending amount of J120 of 5% by weight is designated as "Example 3-1", a blending amount of J120 of 10% by weight is designated as "Example 3-2", and a blending amount of 20% by weight is designated as "Example 3-3". Blowability and wall thickness uniformity were evaluated. The results are shown in Table 1. <Comparative example> As a comparative example, the base resin of the masterbatch was homo-PET. Instead of J120, stretch blow molding was performed and evaluated. The results are shown in Table 1. Homo PET. Was added to the base resin of the masterbatch. It was confirmed that with J120, although good up to the above steps, defects such as defective blow, puncture and uneven thickness of the bottle occurred, and uniform and stable blow molding was difficult.

[0026]

[Table 1]

As is apparent from the test results, according to the method of the present invention, stretch blow molding can be performed, which has an antistatic effect and is sufficiently stable in blowability and bottle thickness uniformity.

[0028]

According to the molding method of the present invention, the periphery of the additive is always covered with the amorphous resin or the resin having a slow crystallization rate, so that the additive particles can be prevented from coming into direct contact with the PET resin. , PE due to the crystal nucleation effect of additives
Crystallization of the T resin can be suppressed. Therefore,
Since it is possible to obtain a PET resin molded product which is uniform in thickness and shape and is stable, and the amount of the additive required for exhibiting the effect of the additive can be compounded without sacrificing the moldability. Various properties and functions such as imparting an antistatic effect or coloring to the PET resin can be freely added. Further, the method of the present invention is to bring the amorphous resin or the resin having a slow crystallization rate into the closest contact with the additive particles which are the crystallization promoting factors at the stage of the additive-containing resin pellets, so that the crystallization thereof is performed. The suppression effect is high, and the amount of the amorphous resin or the resin having a slow crystallization rate can be small.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the concept of a molding method corresponding to claim 1 of the present invention.

FIG. 2 is an explanatory view showing the concept of a molding method corresponding to claim 2 of the present invention.

FIG. 3 is an explanatory view showing the concept of a molding method corresponding to claim 3 of the present invention.

[Explanation of symbols]

 A, B, C Masterbatch A ', B', C'Mixed resin 1 Additive particles 2, 2a Crystal nucleation suppression resin 10, 10a PET resin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 67/08 LNZ C08L 67/08 LNZ // B29K 67:00

Claims (8)

[Claims] 1. An additive-containing resin in which additive particles are filled in a resin having a slower crystallization rate than an amorphous resin or a PET resin or a resin composition containing these resins as a main raw material to suppress the crystallization rate. A method for molding a PET resin, which comprises molding pellets in advance, and molding the mixed resin obtained by mixing the additive-containing resin pellets with a PET resin which is a resin that is easily crystallized. 2. The surface of the additive particles is made of an amorphous resin or PE.
While coating with a resin having a slower crystallization rate than T resin or a resin composition containing these resins as a main raw material,
A PET resin is filled with the coated additive particles in advance to prepare an additive-containing resin pellet having a suppressed crystallization rate, and the additive-containing resin pellet is used as a PET resin that is a resin that is easily crystallized. A method for molding a PET resin, which comprises molding a mixed resin obtained by mixing as a raw material. 3. The surface of the additive particles is made of an amorphous resin or PE.
While coating with a resin having a slower crystallization rate than T resin or a resin composition containing these resins as a main raw material,
Additive-containing resin pellets in which the coating particles are added to an amorphous resin or a resin having a slower crystallization rate than a PET resin or a resin composition containing these resins as a main material to suppress the crystallization rate A method for molding a PET resin, which is prepared in advance and molded by using as a raw material a mixed resin obtained by mixing the additive-containing resin pellet with a PET resin which is a resin that is easily crystallized. 4. The method for molding a PET resin according to claim 1, wherein a PET copolymer is used as the amorphous resin. 5. The PET according to claim 4, wherein the copolymer component of the PET copolymer is a dibasic acid or a dihydric alcohol.
Resin molding method. 6. A crystalline nucleating additive such as a pigment or an antistatic agent is filled in a resin having a slower crystallization rate than an amorphous resin or a PET resin or a resin composition containing these resins as a main raw material. An additive-containing resin pellet having a reduced crystallization rate, which is produced by. 7. A resin having a slower crystallization rate than an amorphous resin or a PET resin on the surface of additive particles having a crystal nucleating property such as a pigment or an antistatic agent, or a resin composition containing these resins as a main raw material. An additive-containing resin pellet that is coated with a substance and is filled with the coated additive particles in a PET resin to suppress the crystallization rate. 8. A resin having a slower crystallization rate than an amorphous resin or a PET resin on the surface of an additive particle having crystal nucleating properties such as a pigment or an antistatic agent, or a resin composition containing these resins as a main raw material. And a resin composition having a slower crystallization rate than an amorphous resin or PET resin or a resin composition containing these resins as a main raw material resin Additive-containing resin pellets with controlled rate of conversion.