JPS5887045A - Method of coating surface of zinc with synthetic resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of coating a zinc surface, such as a galvanized steel material, with a synthetic resin.

Traditionally, metals such as steel have been coated with synthetic resin sheets or plates with adhesives for rust prevention and surface protection, and in particular, materials that do not cause environmental pollution or explosion due to solvents have been used. Methods using hot melt adhesives are being developed. However, for zinc surfaces such as galvanized steel materials, the adhesive strength of hot-melt adhesives is low, and
However, due to immersion in hot water, the adhesive strength decreased significantly and the synthetic resin coating peeled off.

The present invention aims to solve the problems mentioned above, and its gist is that sulfur and/or thiurams, sulfur and/or thiurams, Adhering a synthetic resin layer to the zinc surface using a hot-melt adhesive whose main component is a composition made by mixing 0.7 to 10 parts by weight of a thiazole-based or dithioate-based vulcanization accelerator. This is a synthetic resin coating method for an IF lead coated surface.

The present invention is further particularly useful for manufacturing metal tubes having a zinc surface on the inner surface and lining the inner surface with a thermally expandable synthetic resin tube. In other words, in such lined metal pipes, the inner synthetic resin pipe shrinks more than the steel pipe and tends to reduce its diameter during overcrowding, such as when hot water is passed through and then cooled. Peeling stress acts during this process, which places a complex load on the adhesive. For this reason, in applications where hot water passes through, if there is a weak point at the interface with the zinc surface, the adhesive will not be able to fully demonstrate its performance, and the interface may peel off, causing bulges on the inner surface, or synthetic resin pipes may be damaged due to impact. However, if the method of the present invention is used to manufacture synthetic resin-lined steel pipes that are used under such harsh conditions, it will be possible to avoid the above-mentioned bulges and cracks. When you get the product, you can.

In the present invention, the polyolefin copolymerized with an unsaturated aliphatic carboxylic acid or its anhydride (hereinafter referred to as [acid-containing polyolefin-1)] has good adhesion to metals even when used alone; By adding IJn sulfur accelerator, the adhesion to curved plated surfaces can be improved.

The unsaturated aliphatic carboxylic acids to be copolymerized with the polyolefin used in the present invention include acrylic acid, methacrylic acid, crotonic acid, vinylic acid m, maleic acid, fumaric acid, itaconic acid, mesaconic acid, and ntraconic acid, and are unsaturated Examples of aliphatic carboxylic anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, etc., and these are used in combination or in combination with a content of 0.7 to ? 0. Copolymerization or graft copolymerization is preferably carried out in the range of θ to 2θ. Polyethylene is used as a solid polyolefin,
Polypropylene, Poly/~Ften, HoIJ-9-Mef
Ethylene, propylene, /-butene, cumethyl-pentene, ethylene-propylene copolymer, ethylene-/-butene copolymer, propylene-/-butene copolymer, ethylene-damethyl-/pentene copolymer, etc. /-
Homopolymers such as pentene and their copolymers, ethylene-vinyl acetate copolymers containing these olefins as the main 5Q component, ethylene-vinyl chloride copolymers, ethylene-glynodyl methacrylate co-11 polymers, ethyl-L/ 7. Contains ethyl acrylate copolymer, saponified ethylene vinyl acetate copolymer, etc.

Among these, ethylene/acrylic acid copolymer, ionomer, acrylic acid-modified polyethylene, maleic anhydride-modified polyethylene, maleic acid-modified polyethylene, maleic anhydride-modified ethylene-vinyl acetate copolymer, etc. can be suitably used.

The adhesive composition in the present invention is acid-containing polyethylene 70
1 to 0 parts by weight, 0.7 to 1 sulfur vulcanization accelerator
It is necessary to add 0 parts by weight.

If the amount is less than 0./1 parts by weight, the adhesion to galvanized steel pipes will be insufficient, and even if the amount exceeds 10 parts by weight, the improvement in adhesion will reach a plateau and an unsightly dusty appearance will occur. Examples of vulcanization accelerators include thiurams such as detramethylthiuram disulfide and tetrabutylthiuram disulfide, thiazoles such as benzothiazole and dibenzothiazole disulfide, and Zn.
It can be selected from dithioic acid salts such as diethyldithiocarbamate, zn-dirobethyldithiocarbamate, and the like.

Components of the adhesive include, in addition to those listed in -1-, rosins, terpenes, hydrocarbons, phenol-based adhesive +1 resins, cal/rum carbonate, talc, clay, etc. filling systems, rubber components, and elastomer components. , various waxes, plasticizers, antioxidants, etc. may be added.

In order to adhere a synthetic resin layer to a zinc surface using a two-part adhesive, the adhesive must be melted and applied to the synthetic resin layer surface and/or the zinc surface in advance, or a film adhesive must be applied. The synthetic resin layer and the zinc layer may be placed on top of each other with the adhesive layer interposed therebetween, and the adhesive may be melted by heating for bonding.

In order to manufacture a synthetic resin-lined metal tube according to the present invention, the following steps may be taken.

Thermally expandable synthetic resin pipes are mainly made by extruding synthetic resin such as polyvinyl pyrolyte or polypropylene into a tubular shape, and then stretching it in the axial direction at a temperature above the softening point and below the melting point of the synthetic resin. - It can be used by reducing the diameter by a method and immediately cooling it to make it thermally expandable.

It is preferable to provide the hot-melt adhesive layer on the outer circumferential surface of the synthetic resin pipe in advance to form a laminated pipe for lining because it is easy to apply.For this purpose, the above composition is synthesized using an extruder using a cross-height device. Either extrude it into a ring shape on the outside of the resin pipe, or extrude it into a band shape and wrap it around the synthetic resin pipe to melt-coat it, or form it into a flat film and wrap l'c adhesive around the synthetic resin pipe. method can be adopted.

In order to line the above-mentioned lining laminated tube inside a metal tube, insert the lining laminated tube into the metal tube whose inner surface has been cleaned in advance, and use a method such as using a gas burner or blowing hot air from the outside of the metal tube to open one end of the tube. By heating sequentially from one end or the center to both ends, or by passing heated fluid through the inside of the laminated lining tube, the laminated lining tube is expanded and the adhesive is melted at the same time. It is then glued together.

When lining steel pipes, complicated pretreatment such as treating the galvanized surface of the inner surface of the steel pipe with zinc phosphate was necessary, but according to the method of the present invention, white rust and white rust can be removed by polishing with a wire brush. Sufficient practical strength can be obtained by removing impurities, oil and fat, and cleaning.

Indeed, an intermediate layer with good adhesiveness may be provided between the heat-expandable synthetic resin pipe and the hot-melt adhesive composition to further improve the adhesive strength.

For example, when a polyvinyl chloride resin pipe is used as a thermally expandable synthetic resin pipe, the intermediate layer may contain an adhesive agent such as a rosin resin or a terpene resin for the acid-containing polyolefin that is the main component of the adhesive. A compound containing a polyolefin elastomer such as ethylene-/-butene copolymer or the like can be used.

Since the present invention has the configuration described below, it is possible to apply a synthetic resin coating that is strong and resistant to hot water without performing complicated pretreatment on the zinc surface, and in particular, it is possible to coat the zinc surface with a synthetic resin coating that requires a lot of labor. Synthetic resin-lined metal pipes obtained by applying a synthetic resin coating to the inner surface of metal pipes do not blister on the inner surface of the synthetic resin pipes even under harsh conditions such as passing through hot water, and do not crack due to impact. This is an extremely excellent method of coating a zinc surface with a synthetic resin, as it does not cause any problems.

Hereinafter, it will be explained in more detail with reference to Examples.

In the following example, a synthetic resin-coated metal pipe will be explained.

Example/Ethylene-acrylic acid copolymer (melt intex: 2.0, acrylic acid-containing 5-layer @part) as acid-containing polyolefin, 700-weight sample weight, and the experimental weight in Table 1/~
An adhesive composition containing 11 parts by weight of sulfur extract or vulcanization accelerator as shown in Figure 1, and the same ethylene-acrylic acid as above.
Intermediate layer containing 0 parts by weight of coalescence/θ, 10 parts by weight of ethylene-/-butene copolymer elastomer (melt intex), and 30 parts by weight of terpene phenol resin (softening temperature 9-730°C) 1 composition was prepared.

Next, thermal expansion 1/]: Co-extrusion coating using a cross spatula 1-glue with the front intermediate layer composition on the first side of the polyvinyl chloride pipe and the first half adhesive composition on the second side. A lined river synthetic resin pipe was obtained by providing this. The middle class is 3
F average 1 height SOμ, adhesive layer average height 257
It was 1.

Insert the obtained lined synthetic resin pipe into a galvanized steel pipe (for water supply, size 30A, length Soomm),
The steel pipe surface was heated and lined with a gas heater from one end to the other end so that the steel pipe surface reached /Q00G. Note that the steel pipe was twisted and the inner surface was cleaned with a wire bra.

Next, use the obtained linenog metal tube in the following manner [
The results of evaluating thermal properties are shown in Table 1.

Length 110 from any point on the metal pipe
001n sample was cut out and immersed in gθ℃ warm water for 2 hours.1.
A repeated test of 0 cycles of immersion in 20°C water for 1 hour was performed, and the inner surface of the sample was visually observed, and those with no bulges were judged to be good, and those with any bulges were judged to be bad. .

After that, five test pieces for measuring adhesive strength of the width C θ dragon were cut out from the sample at uniform intervals, and the punching strength was measured at 20 ° C. according to the JWWAK −//L method (Japan Water Works Association standards). It was defined as residual adhesive strength (Ky/ff1). In addition, after cutting out the sample for repeated testing, another 10OOH sample was cut out from the remaining lining metal tube, and the punching strength was measured in the same manner as above to determine the initial adhesive strength.

Table 1 Example Ω As acid-containing polyolefin, the same ethylene as Example/
700 parts by weight of acrylic acid copolymer, the amount shown in experimental form ~9 in Table 2, and ethylene-/-butene copolymer elastomer (Melnyintexno, O) left θ An adhesive containing 1 part of α-pinenephenol softening temperature [/s ooC, 30%] was directly extrusion coated onto the same polyvinyl chloride pipe as in Example/ using a cross-necked tie. I borrowed a laminated pipe for lining.

This laminated pipe was lined with a galvanized steel pipe in exactly the same manner as in Example, and the surface 1 thermal properties were evaluated in exactly the same manner as in Example. The results are shown in Table 2.

The fourth comparison is a fabric board coated with a solvent-based adhesive (chloroprene-phenolic) and lined using a laminated pipe for lining in the same manner as in the example. , G* &/0.

As shown in Table 1, in experimental type 5 in which the addition of sulfur I was less than 0.2 parts by weight, the initial adhesive strength was as high as 30.7.9/d, but after repeated tests, the residual strength decreased. r,tKy
lcr & became extremely small, and a bulge occurred on the inner surface of the synthetic fat pipe due to peeling.

On the other hand, Experiments 6 to 9 of the present invention showed excellent residual strength even compared to the method of Experiment A/0 using a conventional solvent-based adhesive, and had a good appearance. In addition, 10% of sulfur
10 Example 3 Maleic anhydride-modified ethylene-1-ninyl acetate copolymer (melt indensine, θ) as acid-containing polyethylene
700 parts by weight, sulfur/parts by weight, ethylene-/-F-N TE combined elas) mer (Nord Intex λ,
O) S0 heavily defeated part, αbi-phenol (softening temperature/S
Using an adhesive composition containing 30 layers (0°C), a galvanized steel pipe was lined in exactly the same manner as in Example 1, and the heat resistance was evaluated in the same manner as in Example.
Initial adhesion strength 18. But, 27. The adhesive strength was excellent (Ky/d), residual adhesive strength was /q, /Ky/crI, and the appearance was also good.

Patent applicant: Mitsubishi Plastics Co., Ltd. Attorney Hisami Konfuji 14-

Claims (1)

[Claims] A 100% polyolefin copolymerized with an unsaturated aliphatic carboxylic acid or its anhydride is mixed with sulfur and/or a thiuram-based, thiazole-based, or dithioate-based vulcanization accelerator. A method for coating a zinc surface with a synthetic resin, which comprises adhering a synthetic resin layer to the zinc surface using a hot-melt adhesive whose main component is a composition prepared by mixing /~70 parts by weight.