JPH0819384B2 - Pasting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) In the present invention, a soft polyvinyl chloride resin molded article containing a plasticizer is attached to an adherend via an adhesive layer such as a double-sided adhesive tape. It relates to a pasting structure.

(Prior Art) A soft polyvinyl chloride resin containing a plasticizer is inexpensive and excellent in moldability and processability, and is widely used in various fields such as daily necessities, industrial products such as pipes and hoses, transportation equipment and the like.

The types of plasticizers are usually divided into several types such as phthalate ester type, phosphoric acid ester type, and polymer plasticizer type. However, phthalate ester type, especially dioctyl phthalate, is cheap and plastic. It is most used because it is also highly efficient.

However, these low molecular weight plasticizers bleed to the surface when a molded article containing them is used for a long time,
The product tends to be contaminated with stickiness, especially
When this molded article is adhered to another object (hereinafter referred to as "adherend") via an adhesive, the plasticizer migrates to the adhesive layer, and the adhesive strength is reduced, and the adherend is adhered. There was a problem of falling out of. In particular, this problem occurs when the molded product made of soft polyvinyl chloride resin has a sheet shape, a plate shape, or the like.
The area of attachment with the adhesive was relatively large, and this tendency was strong.

For example, in the case of a mall made of soft polyvinyl chloride resin that can be attached to the car body of an automobile, it can be attached to the car body via double-sided adhesive tape, but when exposed to direct sunlight in midsummer, the mall itself rises to 50 ° C or more. It is said that.
The speed at which the plasticizer migrates into the adhesive on the double-sided adhesive tape is
As the temperature increases at an accelerating rate, the long-term durability test of the molding is usually conducted at 70 ℃ or higher. At such a high temperature, a (meth) acrylic acid ester-based resin or a polyester-based resin, which is commercially available as a plasticizer migration inhibitor,
The plasticizer migration prevention function does not work with nitrile rubber-based and urethane-based resins, and polymethylmethacrylate (PMM
Only a slight effect was observed in A).

Therefore, as a means for solving this problem, it has been proposed to interpose a primer layer between the molded product and the pressure-sensitive adhesive layer. (See JP-A-58-185675 and JP-B-1-42987.) (Problems to be solved by the invention) However, even in the above-mentioned conventional technique, the transfer of the plasticizer to the pressure-sensitive adhesive layer is still completely prevented. Has not reached. The above-mentioned conventional technique uses a primer mainly composed of an acrylic polymer, and aims to utilize the migration preventing function of the plasticizer of the acrylic polymer, but it accounts for the total amount of the acrylic polymer. When the proportion is large, the coating performance tends to decrease, and there is a relationship that if the content is stopped at an appropriate coating performance, the effective plasticizer migration preventing function is not exhibited. Even if the migration is blocked,
During the long-term use, the transition gradually progresses and the initial purpose cannot be achieved.

The inventors of the present invention have focused their attention on polymethylmethacrylate after extensive research to solve the above-mentioned problems of the prior art,
When the molecular weight dependence was studied, it was found that the polymer having a weight average molecular weight within a certain range exerts a plasticizer migration preventing function stably for a long time, and has completed the present invention. It is a thing.

(Means for Solving the Problems) 1 of the present invention is an adherend, an acrylic pressure-sensitive adhesive layer, a primer layer containing polymethyl methacrylate as a main component having a weight average molecular weight of 300,000 or more, and a soft polyvinyl chloride resin. A second aspect of the present invention is, in place of an acrylic pressure-sensitive adhesive layer, an acrylic adhesive on both sides of a base material layer, which is characterized in that a molded article is laminated in this order. The gist is the adhesive structure according to claim 1, which is an acrylic double-sided adhesive tape in which an adhesive layer is laminated.

In the primer containing polymethylmethacrylate as a main component used in the present invention, the main component, polymethylmethacrylate, was pursued by the present inventors, and the weight-average molecular weight thereof was 100,000 or more. In particular, at 300,000 or more, migration of the plasticizer was almost prevented even under the condition of 90 ° C., and no decrease in the adhesive strength of the acrylic double-sided adhesive tape was observed. Therefore, the polymethyl methacrylate used in the present invention must have a weight average molecular weight of 300,000 or more.

The method for producing the primer composition is not particularly limited, with respect to the monomer methyl methacrylate,
In addition to the method of mixing a polymerization catalyst such as azobisisobutyronitrile and bulk polymerization, a known method such as solution polymerization may be used.

The upper limit of the weight average molecular weight of polymethyl methacrylate is not particularly limited, but workability during polymerization and
From the viewpoint of workability when applying the primer, it is recommended to use less than 500,000 practically.

There is no particular limitation on the thickness after drying when applying the primer composition to the upper surface of the adhesive layer described below,
From the viewpoint of preventing the migration of the plasticizer, the thicker the better, but from the viewpoint of workability at the time of application and cost, 1 to 20 μm is preferable.

The pressure-sensitive adhesive forming the acrylic pressure-sensitive adhesive layer used in 1 or 2 of the present invention is not particularly limited, but for example, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and other well-known acrylic pressure-sensitive adhesives. More preferably, these are crosslinked. Further, it is optional to use a tackifying resin, an antiaging agent and other additives in combination with these pressure sensitive adhesives.

As a means for forming the pressure-sensitive adhesive layer used in 1 or 2 of the present invention, a pressure-sensitive adhesive is directly applied to an adherend, or a soft polyvinyl chloride resin molded article in which a primer layer composed of the primer composition is previously formed. It may be applied on the primer layer, but it is preferable to use a double-sided adhesive tape as in 2 of the present invention, since a troublesome and uniform layer is formed.

When using a double-sided adhesive tape, as the base material,
A synthetic resin soft foam sheet, such as polyethylene, an ethylene-vinyl acetate copolymer, a (meth) acrylic acid ester copolymer, etc., a chloroprene sheet, paper, a non-woven fabric, an acrylic rubber sheet, etc. are used, and particularly, a synthetic resin soft foam sheet. In the case of using as a material, when the surface of the molded product made of a soft polyvinyl chloride resin or the adherend has irregularities, it deforms following the irregular shape, so that a strong adhesive force can be obtained. For example, an ethylene-vinyl acetate copolymer foamed molded sheet having fine open cells is sliced into an appropriate thickness and the skin layer is removed from the sheet. In the foam-molded sheet from which the skin layer is not removed, the rigidity of the skin layer is high and a large effective adhesive area cannot be obtained even if the foam itself is highly flexible. If the foam is open-celled, the solvent penetrates when the pressure-sensitive adhesive is applied, so it is advisable to laminate a thin synthetic resin film in advance.

As the adhesive formed by the adhesive layer of the double-sided adhesive tape, of course, the above acrylic adhesive is used.

As described above, the method for obtaining the sticking structure according to 1 or 2 is as described above, in which the primer composition is applied to the surface of a molded product made of a polyvinyl chloride resin to form a primer layer, and then a double-sided surface is formed on the primer layer. One of the adhesive surfaces of the adhesive tape is adhered, or an adhesive is applied, and the adhesive surface of the laminate having a three-layer structure thus formed is adhered to a target adherend by pressure. It is preferable that the most effective sticking effect can be obtained.

(Operation) Since 1 of the present invention is configured as described above, it is formed by being interposed between a soft polyvinyl chloride resin molded product containing a large amount of a plasticizer and an acrylic pressure-sensitive adhesive layer. The plasticizer contained in the soft polyvinyl chloride molded product has an acrylic-based plasticizer due to its excellent plasticizer migration prevention function that the primer layer mainly composed of polymethylmethacrylate having a weight average molecular weight of 300,000 or more Transfer to the pressure-sensitive adhesive layer is completely prevented, and even when exposed to high temperature conditions, its curing does not decrease.

Since the second aspect of the present invention is constructed as described above, the plasticizer contained in the vinyl chloride resin molded article is completely prevented from migrating to the acrylic pressure-sensitive adhesive layer for the same reason as described above. Its curing does not decrease even when exposed to high temperature conditions.

Further, the labor of applying the acrylic pressure-sensitive adhesive layer to the adherend is omitted, and the soft polyvinyl chloride resin molded product provided with the primer layer can be easily adhered to the intended place of the adherend. .

(Example) An example of the present invention will be described below.

Example 1. Preparation of Primer Composition To 100 parts by weight of methyl methacrylate monomer, 0.2 parts by weight of azobisisobutyronitrile as a polymerization catalyst was mixed, and after nitrogen bubbling for 20 minutes, the mixture was reacted at a temperature of 60 ° C. for 24 hours and further 100 The bulk polymerization reaction was completed by reacting at a temperature of ℃ for 24 hours.

The reaction was then dissolved in methyl ethyl ketone,
It was prepared so that the solid content concentration was 5% by weight. The weight average molecular weight of the obtained poly (methyl methacrylate) was 35.1 × 10 ^4.
Met.

． Soft Polyvinyl Chloride Resin Sheet Using polyvinyl chloride resin containing 30 parts by weight of DOP as a plasticizer, a strip-shaped sheet having a size of 30 mm × 80 mm × 5 mm was manufactured using a press machine.

． Manufacture of acrylic double-sided adhesive tape 2-ethylhexyl acrylate 89.5 as an adhesive
% By weight, 10% by weight of acrylic acid and 0.5% by weight of 2-hydroxyethyl methacrylate are mixed, and the weight average molecular weight is 6
An isocyanate compound (trade name;
A pressure-sensitive adhesive obtained by crosslinking with Coronate L) was applied to a sheet-shaped carrier to give a pressure-sensitive adhesive sheet having a thickness of 60 μm.
Next, this was transferred to both sides of a tape base material made of polyester film having a thickness of 38 μ, which was previously subjected to corona discharge treatment, to obtain an acrylic double-sided adhesive tape.

． Production of Sticking Structure The primer composition was applied to one surface of a soft polyvinyl chloride resin sheet so that the thickness after drying was 1 μ, and dried at room temperature for 15 minutes to form a primer layer.

Next, attach a strip of top acrylic double-sided adhesive tape measuring 25 mm × 50 mm × 60 μ to the surface of the primer layer at room temperature (23
℃), and then apply the other adhesive layer surface of the above acrylic double-sided adhesive tape to the acrylic coated steel plate that is the adherend.
One-way pressing with a 5 kg roller was applied to make an attachment structure.

Example 2 A patch structure was produced in the same manner as in Example 1 except that 0.1 part by weight of azobisisobutyronitrile was used.

Example 3. Further, in the production of the adhesive structure, a commercially available double-sided adhesive tape (manufactured by Sekisui Chemical Co., Ltd., as an acrylic double-sided adhesive tape to be attached to the primer surface of the sheet coated with the primer used in Example 1 Using the product name; 516K), this was attached to an acrylic coated steel sheet and the peeling force was measured. The result was equal to or more than the peeling force obtained in Example 1.

Comparative Example 1. A patch structure was produced in the same manner as in Example 1 except that the amount of azobisisobutyronitrile was 1.0 part by weight.

Comparative Example 2. A patch structure was produced in the same manner as in Example 1 except that 0.5 part by weight of azobisisobutyronitrile was used.

Comparative Example 3. A patch structure was produced in the same manner as in Example 1 except that the primer was not used.

Comparative Example 4. A patch structure was manufactured in the same manner as in Example 1 except that an aromatic isocyanate-based polyether polyurethane was used as a primer.

Comparative Example 5. A patch structure was produced in the same manner as in Example 1 except that a vinyl chloride-vinyl acetate copolymer was used as the primer.

For each of the above Examples and Comparative Examples, the weight average molecular weight of the primer composition, the amount of transferred plasticizer, and the peeling force were measured. Table 1 shows the results.

 The above measuring methods are as follows.

． Weight average molecular weight A primer composition was prepared using tetrahydrofuran (THF) as a solvent so that the solid content concentration was 5% by weight,
The weight average molecular weight in terms of polystyrene was measured by the gay permeation chromatography (GPC) method.

． Amount of plasticizer transfer A test piece was prepared by stacking an acrylic double-sided adhesive tape on a soft polyvinyl chloride resin molded product before being attached to an acrylic coated steel sheet as an adherend via a primer layer. Was heat-aged at 90 ° C., the double-sided PSA sheet was peeled off, and the weight increase was measured to obtain the amount of transferred plasticizer. A release paper was attached to the opposite surface of the double-sided pressure-sensitive adhesive sheet.

． Peeling force (180 ° peeling force) Similar to the test piece used in the test in the previous section, after the double-sided pressure-sensitive adhesive sheet was pressed against the surface of the primer during the production of the adhesive structure.
After further pressing once with a 2 kg roller, the normal peel force was measured after 20 minutes, and the aging peel force was measured by separately aging at 90 ° C. for 72 hours and then cooling to room temperature. The pulling speed at that time is 200 mm / min. However, in the case of the third embodiment, it is almost 0 °.
The peeling force was close to

Examples 4 and 5 and Comparative Examples 6 to 9 In the production of the adhesive structure, as a base material for the acrylic double-sided adhesive tape, a thickness of 1.2 mm which was previously corona-discharge treated,
10 mm made of polyethylene foam in the same manner as in “Production of acrylic double-sided adhesive tape” above except that a polyethylene foam sheet with an expansion ratio of 20 times was used.
Width acrylic double-sided pressure-sensitive adhesive tape is produced, and the primer composition is applied to the flexible polyvinyl chloride resin sheet having the primer layer formed thereon, and the sheet is adhered onto the primer layer, followed by acrylic coating as an adherend. The steel plate was pressed one-way with a 5 kg roller to give a sticking structure in the same manner as in Examples 1 and 2 and Comparative Examples 2, 4 and 5.

Regarding each of the above Examples 4 and 5 and Comparative Examples 6 to 8,
The peeling force was measured as follows. The results are shown in Table 1.
Shown in

． Peeling force (0 ° peeling force) After the adhesive structure was left at room temperature for 24 hours, the peeling force was measured and used as the normal peeling force. Further, after aged for 72 hours under the temperature condition of 90 ° C., it was cooled to room temperature and left to stand for 3 hours or more to be completely cooled, and then the peeling force was measured to obtain the aged peeling force. The pulling speed at that time is 200 mm / min.

Example 6 Example except that the base material of the acrylic double-sided pressure-sensitive adhesive tape was a 15-fold foam (Sekisui Chemical Co., Ltd., trade name; Volara ES1501) sheet made of an ethylene-vinyl acetate copolymer. A laminated structure was prepared in the same manner as in 5, and the peeling force was measured as described above. Table 1 shows the results.

Example 7 A sticking structure was prepared in the same manner as in Example 5, except that the base material of the acrylic double-sided pressure-sensitive adhesive tape was an acrylic foam (trade name: VHB # 4213, manufactured by 3M, USA) sheet. The peeling force was measured as described above. Table 1 shows the results.

Note) 1. Regarding Comparative Example 3, when the measurement of the amount of transferred plasticizer was continued after 72 hours, it reached a saturated state in 7 days, and the transferred amount at the time of saturation was 35.5% by weight. there were.

2. In peel strength (judgment), ◎: Aged peel strength is far superior to that in the market.

 ◯: Aging peel strength is superior to that in the market.

 Δ: Aging peel strength is almost the same as in the market.

 X: Aging peel strength is inferior to that in the market.

(Effect of the invention) Since the first aspect of the present invention is configured as described above, it is formed by interposing it between a soft polyvinyl chloride resin molded article containing a large amount of a plasticizer and an acrylic pressure-sensitive adhesive layer. The plasticizer contained in the molded product made of soft polyvinyl chloride resin has the excellent plasticizer migration prevention function of the primer layer mainly composed of polymethylmethacrylate having a weight average molecular weight of 300,000 or more. Transfer to the acrylic pressure-sensitive adhesive layer is completely prevented, and even when exposed to high temperature conditions, the curing thereof does not decrease. In addition, this effect does not change regardless of the size relationship between the soft polyvinyl chloride resin molded article and the adherend, so that the range of its application is expanded.

Since the second aspect of the present invention is constructed as described above, the plasticizer contained in the vinyl chloride resin molded article is completely prevented from migrating to the acrylic pressure-sensitive adhesive layer for the same reason as described above. Its curing does not decrease even when exposed to high temperature conditions. Further, since this effect does not change regardless of the size relation between the molded article made of the soft polyvinyl chloride resin and the adherend, the range of application thereof is expanded as described above.

Further, the labor of applying the acrylic pressure-sensitive adhesive layer to the adherend is omitted, and the soft polyvinyl chloride resin molded product provided with the primer layer can be easily adhered to the intended place of the adherend. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C09J 7/02 JJP JKP 133/02 JDA

Claims (2)

[Claims] 1. An adherend, an acrylic pressure-sensitive adhesive layer, a primer layer containing polymethyl methacrylate having a weight average molecular weight of 300,000 or more as a main component, and a molded product made of a soft polyvinyl chloride resin are laminated in this order. A pasting structure characterized by the above. 2. The adhesive structure according to claim 1, which is an acrylic double-sided pressure-sensitive adhesive tape in which an acrylic pressure-sensitive adhesive layer is laminated on both sides of a base material layer, instead of the acrylic pressure-sensitive adhesive layer.