JPS61141744A - Resin composition - Google Patents

Abstract

PURPOSE:To improve the oxygen barrier properties of a hot water circulating pipe for floor heating, by blending a saponified ethylene/vinyl acetate copolymer, polybutene and optionally a modified polyolefin. CONSTITUTION:A saponified ethylene/vinyl acetate copolymer (A) having an ethylene content of 20-60mol% and a degree of saponification of 95% or above, a polybutene (B) and optionally modified polyolefin (C) having a chemically bonded modifier content of 0.01-10wt%, modified with an unsaturated carboxylic acid or anhydride, are blended together. Component A is used in a quantity of 10-50pts.wt. per 100pts.wt. component B. Pref. 1-20pts.wt. component C' is added thereto. As component B, maleic anhydride-modified polybutene is preferred. As component C, malenic anhydride-modified polyolefins (e.g. 2-12C alpha-olefin polymers) are preferred. By improving the oxygen barrier properties, metallic parts of heat exchangers, in hot water circulating passage can be prevented from being corroded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Fields of Application The present invention relates to resin compositions, particularly resin compositions for pipes, and furthermore to central heating by hot water circulation method, particularly for use in floor heating equipment. It has excellent durability and prevents the increase in dissolved oxygen in submerged water due to the penetration of external oxygen.
The present invention relates to a resin composition for hot water circulation pipes, which can significantly suppress corrosion of metal R cracks of heat exchangers, hot water circulation bonders, etc.

B. Conventional technology Conventional floor heating hot water pipes are made of iron;
Pipes made of copper or the like are mainly used. When such pipes are buried in concrete during construction, they are often installed under the floor, and once installed, subsequent repairs are often difficult, and moreover, they usually last for about 50 years, for example. Durability over a long period of time is required. Due to the harsh conditions, seamless pipes are easily obtained, so there is no possibility of leakage from the joints, and they are cheaper, compared to using conventional pipes made of iron or copper. Gelastic pipes are now being used as they are more suitable, without incurring construction costs due to welding operations, etc., and because the pipe material itself does not corrode. However, when such plastic pipes are used in floor heating systems that use hot water circulation, it is an unusual fact that metal parts such as heat exchangers and pumps are noticeably corroded. The calendar eclipse is
Things that were completely unrecognized when using conventional iron and copper pipes have come to be recognized, and the trend towards composite glass pipes is becoming stronger. The reality is that C5, which completely satisfies the corrosion prevention requirements, has not yet been found.

For example, based on the assumption that the corrosion is caused by atmospheric oxygen penetrating and dissolving into hot water through the pipe material, increasing dissolved oxygen, aluminum (AI)
Some attempts have been made to create a composite polyethylene vibrator with 7$1 as the middle layer, but defects such as cracks in the A1 layer have been observed, although the details are not clear, although it seems to be caused by temperature changes. The above requirements have not yet been met.

Furthermore, conventional polyethylene and polypropylene have insufficient heat resistance, and other polyolefins are also usually used after being subjected to radiation crosslinking in order to further improve their heat resistance. In this case, because the degree of crosslinking is high and the crosslinking speed is selected to increase productivity, suitable conditions are usually used, such as irradiation with radiation (electron beam) with an intensity of 12 to 20 Mrad. There is. Saponified ethylene-vinyl acetate monomer (hereinafter sometimes referred to as EVOH) cannot withstand such intense irradiation, and the main chain is inevitably broken and deteriorated, so an EVOH layer was used as the intermediate layer. Even if the multilayer pipe is radiation-crosslinked, it cannot be said that the pipe has a practically satisfactory oxygen barrier property.

Problems to be Solved by the C0 Invention The present inventors have found that the Kel fraction is low during blending and molding, and this operation is possible while causing deterioration of EVO)i, which is a component of the blend. It is desirable to obtain a resin composition for a seamless pipe, especially for hot water circulation, and especially for a floor heating pipe, which satisfies heat resistance, durability, and does not cause corrosion. It is something to do.

A means to solve the D0 problem The present invention provides a solution containing 20 to 60 mol% of ethylene and a degree of saponification of 9.
A resin composition consisting of a saponified ethylene-vinyl acetate copolymer of 5 or more and polybutene (B), and this composition is further modified with a precipitated saturated carboxylic acid or its anhydride and chemically bonded. The modifier's esthetics was 0.
01~] Modified polyolefin (C) with 0 weight ↑ 1 t
This is a resin composition for products, especially for pipes, especially for hot water circulation pipes.

E1 Effects of the Invention According to the present invention, as is clear from the examples described later, even when hot water is circulated through a pipe obtained from the resin composition of the present invention, the rate of increase in dissolved oxygen in the hot water is very small. Because it is a barrel, it is possible to minimize the corrosion of metal parts such as heat exchangers due to the circulation of hot water, and the pipes have excellent heat resistance and durability, so they will not cause problems over a long period of time. It can be used without.

F1 More detailed description of the invention The polybutene used in the present invention has excellent heat resistance and also has good blendability with EVOH, so by using polybutene, the above-mentioned excellent effects can be achieved. It turns out. Here, polybutene means polybutene-
] In addition to the homopolymers of 1, there are also comonomers or graft polymers with polybutene-1 as the main component, ethylene, propylene, monomers, diolefins, carboxylic anhydride compounds, etc. However, other thermoplastic polymers such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and thermoplastic elastomers such as ethylene propylene elastomer and polyisobutylene rubber may be blended with this polybutene within a range that does not impede the purpose of the present invention. In addition, additives such as a lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, a crosslinking agent, a crosslinking aid, a metal terating agent, an inorganic powder, and a coloring agent can also be added. Among these, maleic anhydride-modified polybutene is preferred.

In the present invention, it is effective to further blend a specific adhesive resin with EVOki and polybutene.

By coexisting such a specific adhesive resin in a specific amount, a resin composition for pipes, particularly a resin composition for salt water circulation pipes, has physical properties that are more practically satisfactory.

The adhesive resin used in the present invention is preferably a modified polyolefin that has been modified with an unsaturated carboxylic acid or its anhydride and has a chemically bonded modifier content of 0.01 to 10% by weight. used. Examples of the unsaturated carboxylic acid or its anhydride include acrylic acid, methacrylic acid, methyl methacrylic acid, 8 monobasic acids, maleic acid, 77
dibasic acids such as -'alic acid, itaconic acid, citraconic acid, and hymic acid, or anhydrides thereof, and at least these al are used, but maleic anhydride is particularly preferred. Polyolefins used in the adhesive resin include polymers of α-olefins having 2 to 2 carbon atoms (polyethylene, polypropylene, etc.), and linear copolymers of ethylene and α-olefins having 3 to J2 carbon atoms. low-density polyethylene, α-olefin having a carbon number of Z to 12, and vinyl monomers copolymerizable therewith (fatty acid vinyl esters (vinyl acetate, etc.), acrylic esters (
Examples include copolymers with ethyl acrylate (ethyl acrylate, etc.). Among these, maleic anhydride-modified polybutenes have higher heat resistance and are more preferably used. The degree of modification is in the range of 0.01 to 10% by weight, more preferably 1 to 5% by weight of the chemically bonded modifying agent.

J, VOf-1(A)Fi used in the present invention, %s saponification [95% or more EVO
It is H. If the ethylene content is less than 20 molt, the oxygen barrier property is excellent but the moldability is poor, and the details of this seem to be related to the decrease in affinity with the olefin due to the decrease in the ethylene content. Although it is not clear, it is not possible to obtain a blend with physical properties sufficient to withstand the purpose of the present invention. Also, whether the content is 6
If the amount exceeds 0 molt, although it does not have the above-mentioned drawbacks, the oxygen barrier properties gradually deteriorate and the blend cannot enjoy the effects of the present invention, which is not preferable. It is more preferable that the content is between 25 and 55 mol. The degree of saponification must still be 95% or more; if it is less than 95%, the oxygen barrier properties will be poor and the effects of the present invention cannot be enjoyed.
Blends of two or more EVOHs with different ethylene contents selected from the range of ~60 mol-0 can also be used, and the effects of the present invention can also be enjoyed in this case as well. can.

The EVOH of the present invention includes an olefin having 3 or more carbon atoms such as propylene, and a third component such as metacoacrylic acid, to the extent that oxygen barrier properties are not impaired.
) i, silane-modified gvoa obtained by copolymerizing vinylsilane such as vinylmethoxysilane, vinylethoxysilane, etc. with ethylene and vinyl acetate, and saponifying the resulting copolymer.

E VOHCA) o Blending amount 1d Ho IJ y-f 7
(B) 10 to 50 parts by weight, preferably 15 to 45 parts by weight per 100 parts by weight. If the blending amount of EVOf((A) is less than 10 parts by weight, the effect of inhibiting oxygen penetration into the resulting pipe and increase of dissolved oxygen in wet water will decrease, and
If the amount exceeds the amount of N, the physical properties deteriorate and it is difficult to achieve a practically satisfactory result.

The blending amount of polyolefin/(C) modified with unsaturated carboxylic acid or its anhydride is 100X of polybutene (B).
The amount is 1 to 20 parts by weight, preferably 4 to 17 parts by weight, based on the JI part. If the blending amount of (C) is less than 1 part by weight, the compatibility between polybutene (B) and EVOH (A) is insufficient,
Depending on the extruder, variations in extrusion volume and poor dispersion can easily cause variations in quality.

In addition, the physical properties of more than 20 parts are deteriorated, making it difficult to be practically satisfactory.

In the resin composition of the present invention, it is preferable to add an antioxidant to the resin composition, but since the action and effect of the antioxidant is relatively increased together with the effect of suppressing oxygen penetration, The amount of antioxidant added may be small in order to achieve the same effect. As the antioxidant, for example, 3.5-
Antioxidants known per se such as t-butyl-4-hydroxytoluene, Irganox 010 and Irganox 076 are preferably used.

The resin composition of the present invention is useful as a resin composition for molded products, particularly pipes, especially hot water circulation pipes. In.

There is little risk of cracks etc. The outer diameter of the pipe is 1
The pipe thickness is about 1 to 0.0 to about 1 ml. In addition, the circulating hot water temperature is, for example, 60~
The temperature is 95°C, preferably 60-90°C.

As mentioned above, the resin composition of the present invention is particularly effective as a resin composition for pipes, particularly for ring pipes, but it can also be used as a resin composition for other sheets, films, and laminates. You can also. In addition, various liquids,
It can be used as a resin composition for gas pipes, and also for producing bottles by blow-molding Parinone.The present invention will be further explained below with reference to Examples.

The present invention is not limited to these Examples.

Example] Polybutene-] Density 0.9 for 00Jif part
52 f/cc, melt index 0.5P/1
0 minute high-density polyethylene (Yukalon manufactured by Mitsubishi Yuka Co., Ltd.)
DoBX-50 (trade name) 1 was mixed with 5 parts by weight of a modified polyethylene of 1.5N polyethylene modified with maleic anhydride, and ethylene content 31 mol%, saponification degree 99.3%, melt inodef 221.29%. 10 minutes (190'C12)
EVo)i35x'M,st'' of 6ot load M) was tri-blended and fed to the extruder, using a circular die, 2
Thickness 2.1 wm, outer diameter 2011 at a die temperature of 10°C
11 pipes were obtained.

Water from which dissolved oxygen had been removed using a packed tower filled with metallic tin was passed through the pipe at 50 mK, and the rate of increase in dissolved oxygen in the water was measured at the inlet and outlet of the pipe at a temperature of 70°C. The relative humidity in the atmosphere is ss% (2ot),
The rate of increase in dissolved oxygen was 104 μf/hr.

For comparison, thickness 2. ] A pipe with an outer diameter of 20 m was obtained using only the polybutene-1. Regarding this pipe, the rate of increase in dissolved oxygen was similarly measured. The speed is 360
It was 0μf/hr.

Example 2 High density polyethylene (melt index 0,1f/1
0 minutes, density 1), 955) (Mitsubishi Yuka Yukalon Hard AX-7O (trade name)) and ethylene content! 40 mol%,
Saponified #99.2% melt index 3.5f71
The procedure was the same as in Example 1 except that 0 minutes of EVOH was used. The increase rate of the dissolved oxygen measured in the same manner as in Example 1 was [4''t146 μf/hr].

For comparison, only the polybutene was used and the thickness was 2. ] A pipe with a field side diameter of 20 mm was obtained. The rate of increase in dissolved oxygen is 370
It happened at 0μf/hr.

Example 3 Polybutene-1100 used in Example 1! Ejtlt, 31 mol% ethylene, degree of saponification 99.3%, melt intex 1.2 f/10 min (2 at 190°C) 60
EvU) of 135% was triblended, melt-kneaded in a twin-screw extruder at 230°C, extruded into a strand, cooled, and cut to obtain pellets.

A pipe was obtained from this pellet by the method shown in Example. The increase rate of dissolved oxygen measured in the same manner as in Example 1 was 1
It was 10μf/hr.

For comparison, the melt-kneading and pelletizing operations by cutting were removed using a twin-screw extruder, and the modified polyolefin and EVO) were directly tri-blended for one session, and a vibrator molded product was obtained using a single-screw extruder. The increase rate of dissolved oxygen in the obtained pipe was 325 to 105μ! The quality of swords and vines varies greatly depending on the /hr and measuring pipe, and the quality is not constant.

Example 4 High density polyethylene (melt index 0.1f71
0 minute density 0.955) (Mitsubishi Yuka Yucalon Hard BX-
70 (trade name) and ethylene 40 mol%, saponification degree 99
．． 2 Melt Index 3.5f/10min EVO) 1
The same procedure as in Example 3 was carried out except that 45 parts by weight was used.

Increase rate of dissolved oxygen in the obtained pipe Kid ] 02
Rarely pW/hr.

Claims (1)

[Claims] (1) Ethylene content 20 to 60 mol%, saponification degree 95%
A resin composition comprising the above saponified ethylene-vinyl acetate copolymer (A) and polybutene (B). (2) The resin composition according to claim 1, containing 10 to 50 parts by weight of (A) per 100 parts by weight of (B). (8) The resin composition according to claim 1, wherein (B) is maleic anhydride-modified polybutene. (4) Ethylene content 20-60 mol%, saponification degree 95%
The above saponified ethylene-vinyl acetate copolymer (A),
A modified polyolefin (C) modified with polybutene (B) and an unsaturated carboxylic acid or its anhydride and having a chemically bonded modifier content of 0.01 to 10% by weight.
A resin composition consisting of. (5) The resin composition according to claim 4, which contains 10 to 50 parts by weight of (A) and 1 to 20 parts by weight of (C) per 100 parts by weight of (B). (6) The resin composition according to claim 4 or 5, wherein (C) is a modified polyolefin modified with maleic anhydride.