JPS60135560A - Masking tape or sheet for galvanizing - Google Patents

Abstract

PURPOSE:To improve a masking effect and to obtain a sharp parting line by adhering a chemical resistant film layer to one side of a sheet-like fiber base material and forming a self-adhesive layer which is carbonized in a molten zinc bath on the other surface. CONSTITUTION:A surface film layer 2 consisting of a plastic or synthetic rubber sheet or the like having chemical resistance is provided via an adhesive agent layer 3 on one surface of a sheet-like fiber base material 4 which does not melt in a molten zinc bath. A self-adhesive layer 5 of a thermosetting type or the like which is carbonized in a molten zinc bath is formed on the other surface of the material 4. An inorg. filler such as clay or the like is further incorporated into at least one of the material 4 and the layer 5. Such masking tape or sheet 1 is adhered to an object to be plated by utilizing the layer 5. The layer 2 is melted and is carbonized on the surface of the zinc bath in the plating stage. The org. components of the layer 5 and the body 4 are also carbonized to prevent the exfoliation of the body 4 and therefore the desired masking effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a masking tape or sheet for hot-dip galvanizing.

Structures such as power transmission and communication towers, gymnasiums, and heated swimming pools are usually coated with galvanized steel, which has excellent corrosion resistance.

High-tension construction methods will be used to connect the steel frames and steel pipes of these structures. In this construction method, the parts of the structure to be connected are made non-plated in advance, and the surfaces of these non-plated parts are overlapped and tightened with bolts, etc., and the two are strongly connected by utilizing the improvement in the friction coefficient due to rusting. It is.

Traditionally, two-component epoxy paints have been used for masking to obtain these non-plated areas, so (1)
By mixing the two parts and diluting them with a solvent, (2) painting this 3 to 4 times, (3) performing a curing treatment for 3 to 16 hours after each painting, and (4) making the paint by passing it through a hot-dip galvanizing bath. Because it firmly adheres (hereinafter referred to as adhering) to the plated object such as an iron pipe, a complicated process such as scraping off the adhering paint with a grinder is required.

Conventional masking using epoxy paints has problems in that it takes a long time, involves a large number of steps, is complicated, and moreover, the masked portion must be removed with a grinder after plating.

The applicant proposed a masking material that could solve the above problems by providing a surface film layer with chemical resistance on one side of a sheet-like base material that does not melt in a molten zinc bath, and an adhesive layer on the other side. A masking tape or sheet for hot-dip galvanizing has already been proposed.

When this masking tape or sheet is applied to the part of the object to be plated using the above-mentioned adhesive layer and hot-dip galvanizing is applied by a conventional method, the above-mentioned surface film layer is melted in the hot-dip zinc bath. The zinc floats on the surface of the bath and carbonizes, and the adhesive layer or adhesive layer and sheet-like base material carbonize.
This carbonized layer remains attached to the area to be masked with such low adhesion that it can be easily removed with a wire brush, etc., so the desired masking effect is achieved, and this area is not plated with zinc. .

After plating, this carbonized layer can be easily removed with a wire brush or the like.

In this way, using the above masking tape or sheet not only eliminates the process of forming a masking film required for conventional paint-type masking, but also eliminates the toxicity of organic solvents and hardeners, making it safe and hygienic. You can work in an excellent environment. In addition, during the plating process, the carbonized layer formed from the masking tape or sheet adheres to the object to be plated and achieves the desired masking effect, as described above, but unlike conventional paint-type masking materials, Since it does not stick to the plated object, the masking part can be easily exposed in the finish burning process after plating, which can greatly reduce the number of man-hours and at the same time maintain the accuracy of the plated object.

However, when masking is performed using this masking tape or sheet, the carbonized layer formed from this tape or sheet has low adhesion to the plated object, so the carbonized layer may peel off in the molten zinc bath. can be,
The drawback is that the reliability of masking is not sufficient.

Also, due to the gas generated when this masking tape or sheet is carbonized in a zinc bath, there is a boundary line (hereinafter referred to as a parting line) between the area to be plated and the area to be masked.
There is also the problem that the image may become unclear.

The reason why this parting line becomes unclear is because during plating, the object to be plated is placed in a zinc bath so that the surface to which the masking tape or sheet is applied is vertical.
This is because the generated gas is released along the parting line along the object to be plated, and therefore, of the part of the object to be plated, the part directly above the parting line is not plated.

Therefore, the inventors conducted extensive studies with the aim of solving the above-mentioned drawbacks and providing a more useful masking tape or sheet for hot-dip galvanizing, and as a result, they came up with the present invention.

That is, this invention provides a surface film layer having chemical resistance through an adhesive layer on one side of a sheet-like fiber base material that does not melt in a molten zinc bath, and a pressure-sensitive adhesive that carbonizes in a molten zinc bath on the other side. The present invention relates to a masking tape or sheet for hot-dip galvanizing, characterized in that the sheet-like fiber base material and the adhesive layer contain an inorganic filler.

As shown in the figure, the masking tape or sheet 1 of the present invention includes a surface film layer 2 located on the outermost surface, a sheet-like fiber base material 4 located below it with an adhesive layer 3 interposed therebetween, and a sheet-like fiber base material 4 located below it with an adhesive layer 3 interposed therebetween. and an adhesive layer 5 located at.

The surface film layer 2 is chemical resistant and can withstand preliminary treatments such as degreasing treatment, acid treatment, and flux treatment in the normal hot-dip galvanizing process shown in the table below. This surface film layer 2 is composed of a plastic film or a synthetic rubber sheet. Examples include films of low density and high density polyethylene, polypropylene, tetrafluoroethylene copolymers, fluorinated polyimide, polyamide, etc., and sheets of butyl rubber and ethylene-propylene rubber (EPR). Low-density polyethylene film and high-density polyethylene film are preferred in terms of price and properties. Its thickness is usually about 10-100P.

The adhesive layer 3 may be of any material as long as it adheres the surface film layer 2 to the sheet-like fiber base material 4, and may be one that melts or carbonizes in a zinc bath. Preferably, it is carbonized. This adhesive layer 3
The thickness is usually about 20 to 100P.

The sheet-like fiber base material 4 has a function of protecting the adhesive layer 5. That is, it has the function of preventing the adhesive layer 5 from melting in the molten zinc bath and peeling off from the object to be plated, and supporting the adhesive layer 5 until it becomes a carbonized layer, and also prevents the carbonized layer from peeling off from the object to be plated. It has a function to suppress For this reason, it is necessary that this base material 4 does not melt in the hot dip zinc bath (for example, 440 to 500° C.) in the hot dip galvanizing process. In addition, the base material 4 is preferably one that has good adhesion to the carbonized layer in order to sufficiently fulfill the above function, and for this reason, the base material 4 should be one that contains a component that carbonizes in a molten zinc bath. preferable. according to this,
The intertwining of the carbonized layer with the carbide of the base material 4 improves adhesion.

In view of the above, the most preferable base material 4 is a woven or nonwoven fabric made of carbonized organic fibers. Examples of this carbonized organic fiber include cellulose fibers such as cotton cloth and rayon, and fibers made of aromatic polyamide. Further, as the base material 4, a woven fabric or a non-woven fabric made of inorganic fibers using an organic binder as a component to be carbonized may be used. Examples of this inorganic fiber include carbon fiber, glass, and asbestos. Further, it is also possible to use inorganic fibers that do not use an organic binder, but when such inorganic fibers are used, the adhesion to the carbonized layer may be poor. These sheet-like fibrous base materials 4 are usually used at 20
~100y/m'.

The adhesive layer 5 adheres well to uneven surfaces and rusted surfaces of the object to be plated, and can be carbonized in a molten zinc bath while protected by the sheet-like fiber base material 4, preferably about 440 to 5
Although there are no particular limitations on the adhesive as long as it can be carbonized within 2 to 4 minutes in a zinc bath at 00°C, a thermosetting adhesive is preferably used.

This is because this thermosetting adhesive is difficult to melt and easily decomposes and carbonizes. In addition, since the adhesive layer 5 becomes a carbonized layer in this way, it becomes extremely easy to remove the masking material in the finishing process.

Specific examples of adhesives that can be used include thermosetting polyacrylic acid adhesives, natural rubber adhesives, and synthetic rubber adhesives.

The thickness of the adhesive layer 5 is preferably approximately 20 to 100 P.

In this invention, it is important to include an inorganic filler in at least one of the sheet-like fiber base material 4 and the adhesive layer 5 as described in (iv). The shape of this filler is preferably powder, and within this powder, there are shapes such as spherical, flat, polygonal,
It may be porous or fibrous, and any chemical composition may be used as long as it is inorganic, but it is preferable to use one with an average particle size of 1 to 3 Ofim and an apparent density of 01 to 09. .

Specific examples of this inorganic filler include silicates such as clay, bentonite, aluminum silicate, mica, and white carphone, and powdered materials such as calcium carbonate, glass powder, and antimony trioxide. .

In order to incorporate this filler into the above-mentioned sheet-like fiber base material 4, if this base material 4 is a non-woven fabric, it is necessary to incorporate the filler into the sheet-like fiber base material 4 by using an organic binder in the scooping process (sheet-like process). The above-mentioned filler may be added to. Furthermore, if the base material 4 is a woven fabric, a filler may be included between the fibers during or after the woven fabric fabrication process.

"The amount of filler to be included in the above-mentioned base material 4 is usually 10 to 300 parts by weight, preferably 30 to 150 parts by weight, per 100 parts by weight of the base material if it is included only in the base material. . In addition, if the organic binder contains an inorganic filler in advance, the amount including this filler may be in the range indicated by "-". In addition, together with the base material 4, the adhesive layer 5
When the amount of filler is also included in the base material 4 and the adhesive layer 5, the amount of the filler satisfies the above range and the total amount of filler contained in the base material 4 and the adhesive layer 5 is 100% by weight of the total amount of the base material 4 and the adhesive layer 5. 30 for part
The amount is preferably 50 to 150 parts by weight, preferably 50 to 150 parts by weight.

By including the inorganic filler in the base material 4 in this way, the adhesion strength between the base material 4 and the adhesive layer 5 is increased, and thereby the base material 4 has the ability to protect the adhesive layer 5 as described above. is enhanced. In addition, when the base material 4 is made of organic fibers or inorganic fibers using an organic binder, by including the above-mentioned filler, the proportion of components that are carbonized in the base material 4 is reduced accordingly, thereby reducing generated gas. It also has the effect of making the parting line clearer.

In order to obtain these effects, the amount of filler to be included must be adjusted.
It is preferable to keep the filler in the above range; if the amount of the filler is too small, the above effects cannot be obtained, and if it is too large, the function as a base material will be insufficient.

Moreover, in order to include the above-mentioned filler in the adhesive layer 5, it may be added at the time of blending the adhesive. In this case, if the filler is included only in the adhesive layer 5, it is usually 10 to 300 parts by weight, preferably 30 to 150 parts by weight, based on 100 parts by weight of the adhesive. In addition, if the adhesive contains an inorganic filler in advance, the amount including the amount of the filler may fall within this range. Further, when the filler is included in the base material together with the adhesive layer, it is sufficient that this range is satisfied and the amount of the filler contained in the base material 4 and the adhesive layer 5 is within the above-mentioned range.

In this way, by adding a filler to the adhesive layer 5, the amount of components to be carbonized is reduced and the adhesion between the carbide layer and the object to be plated is improved, and the gas generated can be reduced. can be made clear. In order to obtain this effect, the amount of filler to be included should be within the above range; if this amount is too small, the above effect will not be obtained, and if it is too large, it will not work as an adhesive. It is undesirable because it does not function.

Embodiments of masking using the masking tape or sheet of the present invention configured as described above are as follows.

For masking, the above-mentioned masking tape or sheet 1 is first applied to a portion of an object to be plated, such as an iron pipe, to be masked using an adhesive layer 5. Then,
This is subjected to hot-dip galvanizing according to the steps shown in the table above. Since the surface film layer 2 is chemical resistant, the tape or sheet 1 is not damaged in any way during the degreasing treatment, acid treatment, and flux treatment in the pretreatment process.

In the next plating step, the surface film layer 2 is usually melted and floated on the surface of the zinc bath, where it is carbonized. Further, if the adhesive layer 3 is meltable, it will be carbonized on the surface of the zinc bath like the surface film layer 2, and if it is not meltable, it will be carbonized on the surface of the sheet-like fiber base material 3.
It carbonizes while being supported on it.

In addition, the sheet-like fiber base material 4 prevents the adhesive layer 5 from melting and peeling off from the plated object, and the organic components contained in the base material 4 are carbonized to form the adhesive layer 5. It adheres closely to the carbonized layer due to the entanglement effect, and prevents this carbonized layer from peeling off from the object to be plated in the plating bath. The ability to protect the adhesive layer 5 is further improved when the base material 4 contains an inorganic filler, and when the adhesive layer contains this filler, the carbonized layer Since the adhesion between the adhesive layer 5 and the object to be plated is improved, the carbonized layer formed from the adhesive layer 5 adheres to the area to be masked without peeling off, and the desired masking effect is exerted to mask this area. is not galvanized.

Furthermore, in this plating process, as mentioned above, by including the inorganic filler, the amount of components to be carbonized is reduced accordingly, so that the gas generated is reduced and plating is performed so that the parting line becomes clear.

In the cleaning process, the carbonized layer is easily removed using a wire brush or the like.

As mentioned above, by using the masking tape or sheet of the present invention as a masking material for hot-dip galvanizing, not only can all steps required for conventional paint-type masking be omitted, but also organic solvents and curing agents can be removed. The work can be carried out in an environment that is excellent in terms of safety and health as there is no toxicity caused by

Furthermore, the carbonized layer formed in the plating process does not peel off from the plated object, resulting in high masking reliability, and the parting lines are clearly formed, resulting in high plating accuracy. In addition, in the finishing process after plating, the carbonized layer can be removed with a wire brush or the like to easily expose the masked area, resulting in a significant reduction in man-hours and at the same time maintaining the precision of the plated object.

Examples of this invention will be described below.

Example 1 Synthetic rubber adhesive solution (solid content 20% by weight; BPS-4300 manufactured by Toyo Ink Manufacturing Co., Ltd. diluted with toluene)
A 1.801 m thick aluminum hydroxide-added flame retardant paper (organic cellulose paper containing 786% by weight of aluminum hydroxide = Toyo Pulp Cosmo-185RGS) was immersed in the solution, and then dried at 120°C for 10 minutes. A double-sided adhesive sheet with a thickness of 250 μm was obtained using aluminum hydroxide-added flame retardant paper as a base material.
A masking sheet for hot-dip galvanizing of the present invention was obtained by pasting a Q1lIn low-density polyethylene film.

Example 2 Antimony trioxide (sb2o3) powder was added to a thermosetting acrylic adhesive toluene solution (solid content: 40% by weight; Dainippon Ink (TD-3213 manufactured by Kiki)) to reduce the solid content of the adhesive solution. This powder was added at a ratio of 100 parts by weight to 100 parts by weight and stirred uniformly, and then an aluminum chelate compound hardener (Dainippon Ink Co., Ltd.
A-], 0], CL) were added at a ratio of 5 parts by weight of this curing agent to 100 parts by weight of the solid adhesive, and the mixture was stirred until the whole was homogeneous to form an adhesive composition. Obtained.

After immersing a rayon nonwoven fabric (Kojin Co., Ltd.'s Bonlight N-40) with a thickness of about 120P in this composition, the composition was mixed with two squeezing rods so that the amount of antimony trioxide was 200y/w? After adjusting the adhesion amount of
A double-sided adhesive sheet was obtained.

A 12-tile thick tetrafluoroethylene-ethylene copolymer film (AFLEX12N manufactured by Asahi Glass Co., Ltd.), which had been corona-treated on one side, was attached to one side of this double-sided adhesive sheet, with the corona-treated side serving as the adhesive surface. A masking sheet for hot dip galvanizing was obtained.

Example 3 Mica powder (Mica Powder K manufactured by Wakita Kogyo ■) was added to a synthetic rubber adhesive solution (same as in Example 1), and 50 parts by weight of mica powder was added to 100 parts by weight of the solid content of the adhesive solution.
It was added in a proportion of parts by weight and thoroughly stirred to obtain a uniform adhesive composition.

This adhesive composition was applied to asbestos paper (composed of asbestos and an organic binder, with an asbestos content of about 85% by weight) having a thickness of 125 pn; Inolgo A3 manufactured by Johnsman Building Co., Ltd.
000), the amount of mica powder is 250?
/nf, and then dried at 20'C for 10 minutes to form a 260P thick double-sided adhesive sheet with asbestos paper as the base material. Obtained. One side of this double-sided adhesive sheet has a thickness of 30p.
A masking sheet for hot-dip galvanizing of the present invention was obtained by pasting a high-density polyethylene film.

The masking sheets for hot-dip galvanizing obtained in Examples 1 to 3 above were each cut into tape shapes with a width of 25 mm.

Each of these tapes is 4 mm thick.

This was used as a test piece by wrapping the iron plate once around the center of a 50 mm wide and 4.00 am long iron plate without entraining air. Ten test pieces were prepared for each of Examples 1 to 3. These test pieces were hot-dip galvanized according to the steps shown in the table above.

In the pretreatment process, drug concentration,
Even though the harshest conditions were adopted in terms of treatment temperature and treatment time, no damage was observed in any of the surface film layers of the test pieces using the masking tapes of Examples 1 to 3. .

In the next plating process, the surface film layer of the tape of each test piece melts and floats on the surface of the molten zinc bath, becoming carbonized, and the organic components contained in the base material and adhesive layer are carbonized. It adhered closely to the iron plate and exhibited a masking effect. In addition, the parting line was clear in all cases.

For reference, a masking sheet for hot-dip galvanizing was obtained in the same manner as in Example 1, except that organic cellulose containing no aluminum hydroxide was used instead of flame-retardant paper containing aluminum hydroxide (Reference Example 1). ). In addition, the same procedure as in Example 2 was carried out except that antimony trioxide was not used (
Reference Example 2), Example 3 except that mica powder was not used.
In the same manner as (Reference Example 3), masking sheets for hot-dip galvanizing were obtained.

Using the masking sheets obtained in Reference Examples 1 to 3 above, the same procedure as in Examples 1 to 3 was carried out, and 10
Test pieces were prepared. These test pieces were hot-dip galvanized according to the steps shown in the table above. In the pretreatment step, no damage was observed in the surface film layer of the tape of any of the test specimens, as in Examples 1 to 3. In the next plating process, the carbonized layer peeled off in the number of test pieces shown below, and no masking effect was obtained with these peeled test pieces. In addition, in the case where the carbonized layer did not peel off, the parting line was unclear and the masking effect was also slightly inferior.

Number of peeled pieces (out of 10 each) Reference example 15 Reference example 25 Reference example 32

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a partial sectional view of a masking tape or tape for hot-dip galvanizing according to the present invention. ■... Masking tape or sheet, 2... Surface film layer, 3... Adhesive layer, 4... Sheet-like fiber base material, 5... Adhesive layer.

Claims (1)

[Claims] +1) A surface film layer having chemical resistance is provided on one side of a sheet-like fiber base material that does not melt in a molten zinc bath via an adhesive layer, and the other side is carbonized in a molten zinc bath. 1. A masking tape or sheet for hot-dip galvanizing, characterized in that an adhesive layer is formed, and at least one of the sheet-like fiber base material and the adhesive layer contains an inorganic filler. (2) A masking tape or sheet for hot-dip galvanizing according to claim (1), wherein the sheet-like fiber base material is made of organic fibers or inorganic fibers using an organic binder.