JPS6211748A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition having suppressed thermal degradation of a constituent copolymer in molding and giving a reusable scrap composition such as regrind, by compounding a propylene-based resin, an ethylene-vinyl alcohol copolymer and a hydrotalcite-type compound metal hydroxide. CONSTITUTION:The objective resin composition can be produced by compounding (A) a propylene-based resin (e.g. isotactic polypropyene) with (B) an ethylene-vinyl alcohol copolymer (preferably a saponified copolymer produced by saponifying an ethylene-vinyl acetate copolymer having an ethylene content of 25-50 mol% to a saponification degree of >=00 mol%) and (C) a hydrotalcite-type compound metal hydroxide (preferably the hydroxide of formula). The ratio of A:B is preferably 10<6>:1-1:10<2>, and the amount of the component C is 10<-5>-1 wt% based on the sum of the components A and B. EFFECT:The scorch, deposition to die face, etc., can be suppressed to give a molded article having excellent appearance and mechanical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a resin composition containing a propylene resin and an ethylene-vinyl alcohol copolymer. The present invention relates to the above resin composition whose deterioration is effectively suppressed.

PRIOR ART Ethylene-vinyl alcohol copolymer is one of the resins that has the best permeability to gases such as oxygen among various resins.Using this property, it can be used to make cuttle, cup, etc. Widely used in fields such as packaging containers and films.

The ethylene-vinyl alcohol copolymer is sensitive to humidity, and has the disadvantage that the oxygen permeability coefficient becomes about an order of magnitude larger under high humidity conditions such as 100 S RH. In order to improve this drawback, ethylene-
The vinyl alcohol copolymer is used in a blend with a low water absorbency resin that has excellent permeability to water vapor and water, such as polyethylene or polypropylene, or a gas barrier layer containing the copolymer is used with the water absorbent resin. A widely used method is to create a laminated structure sandwiched between inner and outer surface layers of ethylene-vinyl alcohol copolymer to reduce the influence of humidity on the ethylene-vinyl alcohol copolymer.

Therefore, when manufacturing packaging containers from such compositions or laminated structures, the ethylene-vinyl alcohol copolymer tends to deteriorate, especially when propylene resins are used among the low water absorbency resins mentioned above. Reeds, black-like deposits (scorch), etc. occur inside the extruder, or stick to the die lip during extrusion, resulting in the formation of stick-like substances (stick), which may also affect the appearance characteristics and mechanical properties of the molded product. A problem arises in that the characteristics are significantly impaired.

Also, when manufacturing a packaging container from the above-mentioned composition or laminated structure? In the case of blow molding such as a tortoise molding, cracks due to pinch-off inevitably occur, and in the case of cut molding, regrinding of punching scraps, etc. inevitably occurs, and their reuse is necessary from the standpoint of resource conservation. This scrap composition such as regrind is made of a blend containing a low water absorption resin such as a propylene resin and an ethylene-vinyl alcohol copolymer.

If this scrap composition contains a propylene resin, the above-mentioned tendency of deterioration of the ethylene-vinyl alcohol copolymer will become even more pronounced if the composition is reused for molding containers, etc. The reuse of these scrap compositions is thus hampered.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a resin composition containing a propylene resin and an ethylene-vinyl alcohol copolymer, which eliminates the above-mentioned conventional drawbacks.

Another object of the present invention is to provide a resin composition capable of effectively reusing a scrubbing composition of a blend of a propylene resin and an ethylene-vinyl alcohol copolymer produced as a by-product during molding. It's about doing.

According to the present invention, there is provided a resin composition characterized by containing a propylene resin, an ethylene-vinyl alcohol copolymer, and a hydrotalcite type composite metal hydroxide.

Preferred Embodiments of the Invention An important feature of the present invention is that a hydrotalcite type compound and an alloy metal hydroxide are blended into a blend containing a propylene resin and an ethylene-vinyl alcohol copolymer.

As mentioned above, when a blend containing a propylene resin and an ethylene-vinyl alcohol copolymer is applied to mold a container, etc., the ethylene-vinyl alcohol copolymer deteriorates, causing black color to the screw etc. during cross-wire melt extrusion. In addition to causing inconveniences such as scorched matter (scorch) and sludge, this also reduces the appearance characteristics of the molded product due to discoloration, etc., and reduces flavor due to the smell of resin decomposition products.
This results in a decrease in mechanical properties such as impact resistance.

According to research by the present inventors, such deterioration of ethylene-vinyl alcohol copolymer is caused by titanium trichloride (TiCts), which is contained as a catalyst residue in propylene resin.
It is assumed that the main cause is cross-linking reaction or molecular cleavage due to the reaction residues and the like.

In other words, as a propylene polymerization catalyst, Ziegler-
Natsuta catalyst (Alkylaluminum such as Tict3. At(CH3), etc.) is used, but the propylene resin contains a small amount of T I CL or its reactant as a catalyst residue. It is thought that because it coexists with the ethylene-vinyl alcohol copolymer that has been exposed to the melting temperature during this process, crosslinking reactions and molecular scission of the copolymer are promoted, resulting in so-called deterioration.

Side light, ethylene-vinyl alcohol copolymer, Ti
ct, (1100pp)t'rio□(l fb
).

At20. (1%) respectively and heated to 260°C. Melt 70-rate (260°C.

2160g) is shown in Fig. 1. According to this diagram, TiO□ (curve B) and At20. (Curve C)
The change over time of the one to which TiC2, (curve A) was added was almost the same as that of the ethylene-vinyl alcohol copolymer alone (curve D), whereas the amount added to TiC2, (curve A) It will be understood that the decrease in melt index is remarkable even though the amount is significantly lower than that of TiC2 and the like.

In addition, scrap compositions such as regrind have already been subjected to severe operations such as melt extrusion, and the ethylene-vinyl alcohol copolymer in the composition has already deteriorated. Therefore, when this scrap composition is reused for molding containers, etc., the catalyst residue 'r t
It is thought that the deterioration of the ethylene-vinyl alcohol copolymer progresses rapidly due to the action of ct3 and the like.

In the present invention, such thermal deterioration of the ethylene-vinyl alcohol copolymer is prevented by blending a hydrotalcite type composite metal hydroxide.

This hydrotalcite type composite metal hydroxide has the general formula, y12 +, y1″F(OH)2X+33F-2Z(A
2,・aH20−・・・・−(1) In the formula, M2+ is M
A divalent metal ion such as g, M3+ is a trivalent metal ion such as At, and a positive number satisfying the following.

Indicated by

Among these composite metal hydroxides, the compound represented by the formula % (2) is a natural mineral known as hydrotalcite, and this mineral and its congeners are disclosed in the application filed by Kyowa Chemical Industry Co., Ltd. Special Publication No. 47-32198,
It is synthesized by the method described in No. 48-29477 and No. 48-2947.

In the present invention, among these hydrotalcite-type composite metal hydroxides, the hydroxide represented by the formula % (3) is particularly suitable.

The above-mentioned hydrotalcite-type composite metal hydroxide has an excellent ability to capture chlorine ions, and in the present invention, it is used to mask T i C13 contained in propylene resin, and to mask TiC13 contained in propylene resin. This prevents deterioration due to crosslinking of the alcohol copolymer.

Taking the compound represented by formula (3) as an example, the masking function of this hydrotalcite-type composite metal hydroxide is shown by the following formula, for example.

Mg4. s At2(OH) 1. Co, 3.5H
20+2HC2→Mg4.5AL2(OH)13C2z
+4.5HzO+CO2--(') In the present invention, the hydrotalcite-type composite metal hydroxide contains 10-5 to 5% by weight, especially 10 to 1
It is contained in an amount of - by weight.

If the amount exceeds the above range, the desired masking effect will not be achieved and deterioration of the ethylene-vinyl 7/l/coal copolymer may be prevented. It does not adversely affect the mechanical properties of the product or the flavor of the molded product.

In the present invention, as the ethylene-vinyl alcohol copolymer, an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 moles, especially 25 to 50 moles, and a saponification degree of 96 moles or more, especially A saponified copolymer obtained by saponifying the copolymer to a content of 99 mol or more is used. This saponified ethylene vinyl alcohol copolymer should have a molecular weight sufficient to form a film.

In general, it is desirable to have a viscosity of 0.01 dt/9 or more, particularly 0.05 di/E or more, as measured at 30° C. in a mixed solvent with a weight ratio of phenol:water of 85:15.

As the propylene resin, a Ziegler-Natsuta catalyst is used during polymerization or copolymerization, and in particular, a propylene resin with a water absorption rate of 0.5 inches or less, preferably 0.1% or less as measured by ASTM D570 is used. used,
Representative examples include crystalline polymers such as isotactic/lipropylene, ethylene-propylene copolymer, glopylene-butene-1 copolymer, and ethylene-propylene-butene-1 copolymer. I can do it.

In the resin composition of the present invention, ethylene-vinyl alcohol copolymer (EVOH) and propylene resin (pp)
Although EVOH:PP may be present in any ratio by weight, it is generally preferred that EVOH:PP be present in a weight ratio of 1:10 to 1000:1, particularly 1.10 to 100:1.

During regrind, which occurs as a by-product during molding, EVOH
:PP=1:2000 to 1:3, EVOH
The amount of propylene resin is considerably excessive.

The resin composition of the present invention is very effective in that scrap compositions such as the above-mentioned regrite can be used as constituent components.

The resin composition of the present invention may contain thermoplastic resins other than the above-mentioned ethylene-vinyl alcohol copolymer and propylene resin.

Ethylene-vinyl alcohol copolymer is usually used as a laminate structure sandwiched between inner and outer surface layers of low water absorbency resin such as polypropylene to reduce the influence of humidity, but ethylene-vinyl alcohol copolymer Since the copolymer and the low water absorption resin generally do not have adhesive properties, an adhesive resin is blended into one or both of these resin layers, or an adhesive resin layer is provided between the two resin layers. Naturally, these adhesive resins will also be mixed into the regrind blend. Further, when the above-mentioned blend is coextruded with another low water absorbency resin and/or an ethylene vinyl alcohol copolymer, an adhesive resin may be mixed into the blend.

Such adhesive resins include calgenic acid.

Carganic acid anhydride, carboxylate, cardenic acid amide,
Carbonyl (-C-) based on caldic acid ester, etc.
groups in the main chain or side chains, 1 to 700 m-eq/10og resin, especially 10 to 500 m-eq.
Examples include thermoplastic resins containing at a concentration of meq/100g resin. Suitable examples of adhesive resins include ethylene-acrylic acid copolymers, ionically crosslinked olefin copolymers, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene-acrylic acid grafted polyolefins, ethylene-vinyl acetate copolymers, These include polymerized polyester, copolymerized polyamide, etc.

These cal-containing thermoplastic resins generally have a content of 200 to 0.01 parts by weight per 100 parts by weight of EVOH and pp.
It is present in an amount of parts by weight, especially from 100 to 0.1 parts by weight.

In addition to the above-mentioned adhesive resin, high-density polyethylene may be used, for example, in a range of 4σ weight % or less.

Other thermoplastic resins such as linear low density polyethylene and ionomers may also be blended.

In the resin composition of the present invention, even when other thermoplastic resins such as those mentioned above are blended, the masking effect of the hydrotalcite-type composite metal hydroxide is not lost, thus making regrind etc. effective. It is possible to reuse it.

The resin composition of the present invention is melt-extruded and molded into a container, film, sheet, or the like. At this time, the molded article may be formed from a single layer of the composition, or it may be coextruded with other resins or resin compositions to form a molded article with a laminated structure.

Other resins used for coextrusion with the resin composition of the present invention include low water absorption resins, ethylene vinyl alcohol copolymers, adhesive resins, and blends of two or more of these. Suitable examples of the layer structure are as follows: the resin composition of the present invention is represented by BL, the low water absorption resin is represented by LMR, the ethylene-vinyl alcohol copolymer is represented by EVOH, and the adhesive resin is represented by AD. However, the present invention is of course not limited to this.

Single layer structure BL double layer structure BL/LMR, BL/EVOH three layer structure BL/EVOH/BL, BL/EVOH+AD/BL.

BL/EVOH+AD+LMR/BL, EVOH/AD
/BL, BVOH/BL/LMR Four-layer structure LMR/BL/EVOH/LMR+AD%LMR/BL
/EVOH+AD/LMR Five-layer structure BL/AD/EVOH/AD/BL%LMR/AD/E
VOH/AD/BL, BL/EVOH/BL/EVOH
/BL Six-layer structure LMR/AD/EVOH/AD/BL/LMR Seven-layer structure LMR/BL/AD/EVOH/AD/BL/LMR Eight-layer structure LMR/BL/LMR/AD/EVOH/D/BL/
LMR Optical layer structure LMR/BL/LMR/AD/EVOH/AD/LMR
/BL/LMR.

The resin composition of the present invention is melt-kneaded, for example, in an extruder, and then extruded into a predetermined shape through a die such as a T-Guy or a circular die.

In the case of multilayer coextrusion, each resin layer is melt-kneaded in an extruder corresponding to the resin layer, and then extruded through a multilayer die.

The molded product can take the form of a film, a sheet, a dζtor or a tube, a parison or pipe for forming, a shape for forming a bottle or a tube, etc.9.

Formation of a mold from a parison, pipe or preform is easily accomplished by cutting the extrudate through a pair of split molds and blowing fluid into the mold. Further, after cooling the pipe or the Noriform, it is heated to a stretching temperature, stretched in the axial direction, and blow-stretched in the circumferential direction using fluid pressure, thereby obtaining a stretched blower or the like.

Furthermore, by subjecting the film or sheet to vacuum forming, pressure forming, stretch forming, plug assist forming, or the like, a bag-shaped, tray-shaped, or other packaging container can be obtained.

Effects of the Invention In the resin composition of the present invention, thermal deterioration of the ethylene-vinyl alcohol copolymer component in the composition is effectively suppressed during molding, etc.; It is possible to obtain a container whose gas barrier properties do not deteriorate due to the influence of humidity without impairing its external appearance or mechanical properties such as impact resistance.

By preventing heat deterioration of the mataethylene-vinyl alcohol copolymer component, extrusion properties are also good, and there is no occurrence of so-called scorching, surging, fish eyes, etc.
Extrudates free of defects such as dirt are obtained.

Furthermore, according to the present invention, a remarkable advantage has been achieved in that scrap compositions such as regrind produced as by-products in the molding of containers, etc. can be reused for molding containers, etc., and the present invention is advantageous from the viewpoint of resource saving. Extremely useful. Moreover, when the resin composition of the present invention is used to mold containers, etc., the composition contains a scrap composition such as regrind, and the hydrotalcite-type composite metal hydroxide is contained within the above-mentioned range. It is possible to reuse it as is, as long as it lasts.

The invention is illustrated in the following example.

Example 1゜Density: 0.91g slag, (ASTMD-1505), Melt index: 5.99/10 min,
(ASTMD-1238) tactical polypropylene (PIF-1) with an ethylene content of 48 mole, a saponification degree of 96.1%, and a melt-fired (
(MI, ASTM D-1238) is 20 fi/
For 10 min, 0.05 PHR of DHT-4A (Kyowa Kagaku Kogyo Co., Ltd.'s Hydrotal) was mixed with ethylene-vinyl alcohol copolymer (EVOH-1) at a mixing ratio (weight ratio) of 90:10. Cytotype compounds) are added,
After dry blending, this dry blend was used in a Prabender Plastograph manufactured by Brabender, West Germany, at a chamber temperature of 230°C and a rotor rotation speed of 65 rpm.

Kneading was carried out for 30 minutes under these conditions.

Hereinafter, the kneaded product with is referred to as A. In addition, for comparison, we also prepared crosstalk products (PP-1 and EVO) to which DHT-4A was not added.
The mixture ratio with H-1 was the same) was also obtained under the same conditions as above (hereinafter, this kneaded product will be referred to as B).

A kneaded product of these 2s A and B! A sheet with a thickness of about 300 μm was produced by high-pressure pressing at &250°C. Then, the unit area (1 m) of each of the sheets A and B was magnified 100 times using a universal projector, and burnt (black deteriorated material) was observed. The number of burnt spots observed from sheet A was 1/1α2, while the number of burnt spots observed from sheet B was 7.
It was 2 pieces/1 crn2.

Example 2゜Density is 0.90 g (ASTMD-1505)
, melt index is 1.1.9/10m1n,
(ASTMD-1238) ethylene-propylene copolymer (contains 5 wt% ethylene, hereinafter referred to as PP)
1 part by weight of DHT-4A (described in Example 1) was added to 100 parts by weight, and extrusion was carried out using a built-in screw with a diameter of 65 cm and an effective length to diameter ratio (L/I) of 22. The PP+DHT mixture was prepared according to the method described above. The conditions for beletizing at this time are that the set temperature of the extruder is 200℃, 200℃, and 230℃ from the feed section of the screw.
The temperature was 230°C, the screw rotation speed was 45 rpm, and the discharge rate was 50 kg/hr. Hereinafter, this mixture will be referred to as 5-pp.

On the other hand, the ethylene content is 27 mole and the saponification degree is 99.
5 molti, melt index (ASTMD-123
8. However, the measurement temperature is 210°C) 100 parts by weight of ethylene-vinyl alcohol copolymer (EVOH) above DH
Adding 0.5 parts by weight of T-4A and using the same extruder and pelletizing conditions as above, the EVOH + DHT mixture (
pellets) were obtained. Below, this pellet is S-EVO
Write it as H.

After dry blending each of these pellets at the mixing ratio shown in Table 1 (each unit is 'kg' in the table), each mixture was transferred to the above-mentioned extruder and a cylindrical &) layer with an internal volume of 450 cc. Bottles (average wall thickness: approximately 500 μm) consisting of each of the above mixtures were molded using a mold. The extrusion and molding conditions are blow molding conditions of 5.0 k.
l? / cm2, all other conditions were the same as the pelletizing conditions described above. Sampling of each bottle began about 1 hour after the start of extrusion. Approximately 200 bottles of each type were collected. Below are these &)
C, D, and C, respectively, according to the marks listed in Table 1.
E.

They are written as F, G, H, I, and J.

For each of the eight types of bottles obtained, sheets C to J were produced using a high-pressure press in the same manner as described in Example 1, enlarged under the same conditions using the universal projector described in Example 1, and charred ( (black degraded product) was observed. The results are shown in Table 2. Table 2
Each numerical value in , means the number of bottles in which scorch was observed among each sheet pressed from the center of the body of 100 YJR bottles per type. Therefore, it is recognized that the smaller the value, the less "burntness in the bottle."

Next, in this test, 3 people tested these 8 types of compositions to determine how many minutes after starting the extruder, 1" (rubber-like substance) would occur at the die lip of the extruder. The workers judged visually.The results are also shown in Table 2.In Table 2, each person summarizes the average value of the answers of the above three people in 5 minute units. It can be said that the smaller the value, the slower the occurrence of "stain", that is, the composition 1 is better in terms of resistance to deterioration.

Furthermore, after extrusion molding for about 2 hours was completed, the screw was removed from the extruder, and the three workers visually judged the state of "scorch" adhesion from the compression part to the metering part of the screw. The results are also shown in Table 2. In the same table, each person is given a 1 if there is no scorch on the screw, and a 2 if there is some scorch on the screw, based on the visual judgment of the three workers mentioned above.
, (]ii) 3.4ψ if there is some burnt material
A score of 4 was given for cases where there was significant accumulation of scorch on the screw, and the average value of each answer is shown. Therefore, the smaller the number, the more
It can be determined that the degree of scorching on the burner is small.

From the results in Tables 1 and 2, it can be seen that when a hydrotalcite compound is added to at least one of PP or EVOH synthetic resins, "scorching" and "staining" occur during melt extrusion of PP/EVAL mixtures. etc., it becomes possible to significantly prevent the deterioration of the resin.

Table 1 Table 2

[Brief explanation of the drawing]

g l Figure C, ethylene-vinyl alcohol copolymer has Tict, , TiO2 and At20. FIG. 3 is a diagram showing the relationship between time and melt flow rate for the respective additives. Figure 1

Claims (2)

[Claims] (1) A resin composition comprising a propylene resin, an ethylene-vinyl alcohol copolymer, and a hydrotalcite-type composite metal hydroxide. (2) Contains propylene resin and ethylene-vinyl alcohol copolymer in a weight ratio of 10^7:1 to 1:1000, and contains 10% of hydrotalcite-type composite metal hydroxide per total amount of both resins. A composition according to claim 1 containing from 5 to 5% by weight.