JP2003171628A - Foam sheet having thermosensitive adhesive layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive foam sheet having a thermosensitive adhesive layer evenly formed thereon and dispensing with the release paper. <P>SOLUTION: The foam sheet has a thermosensitive adhesive layer coated on at least one of its surfaces. The adhesive is non-adhesive at room temperature but turns adhesive when heated and stays adhesive for a long period of time thereafter. The foam sheet has a contact angle of not smaller than 70° but not larger than 105°. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to automobiles, houses,
In electronic devices and other fields, it relates to a foam sheet to be adhered to an adherend for the purpose of soundproofing, dustproofing, airtightness and moistureproofing, etc., and a method for producing the foamed sheet. TECHNICAL FIELD The present invention relates to a foam sheet provided with a heat-sensitive adhesive layer, in which the property is expressed and the tackiness is maintained after the expression, and a method for producing the foam sheet.

[0002]

2. Description of the Related Art A heat-sensitive adhesive which is non-adhesive at room temperature, but which develops adhesiveness by heating and maintains its adhesiveness after expression, comprises a thermoplastic resin, a tackifier and a solid plasticizer as a basic composition. And a polymer emulsifier system obtained by emulsion-polymerizing a radical polysynthetic monomer such as an acrylic system in the presence of an unsaturated carboxylic acid-based radical polymer (water-soluble resin),
It is conventionally known. Further, a heat-sensitive adhesive sheet obtained by coating such a heat-sensitive adhesive on a sheet is also conventionally known. Examples of the sheet base material include cloth, paper and plastic films.

[0003]

The heat-sensitive adhesive is often used as a water-dispersed pressure-sensitive adhesive represented by a well-known delayed tack-type pressure-sensitive adhesive, and the heat-sensitive adhesive sheet is a heat-sensitive adhesive. It is manufactured by applying the agent to the sheet surface and drying it by an appropriate method. Therefore, when the sheet base material is cloth, paper, plastic film, or the like, a uniform coating film can be formed by coating (coating). However, when the sheet base material is a foam sheet, since it has a large number of cells on the surface to be coated and has characteristics peculiar to the foam such as high flexibility, it is used as a water-dispersed pressure-sensitive adhesive. When used, it is not possible to form a uniform coating film on the coated surface of all foam sheets. This is because, for example, the applied heat-sensitive adhesive may be absorbed or may enter the cell, resulting in failure to form a coating film or uneven coating.

In view of the above problems, it is a first object of the present invention to provide a foam sheet having a uniform coating of a heat-sensitive adhesive and a method for producing the foam sheet.

In addition, as a conventional foam sheet, after sticking a so-called double-sided tape in which a pressure-sensitive adhesive is taped on one surface of the foamed body, the release paper (release liner) of the double-sided tape is peeled off when used, and adhered. There are some that adhere to the body (adhesion), but this requires a tedious work of peeling just before adhering to the adherend, and the peeled release paper causes processing problems as dust, especially in waste disposal. It is also an environmental issue.

A second object of the present invention is to provide a foam sheet which does not require a release paper for covering the pressure-sensitive adhesive layer and a method for manufacturing the foam sheet, even if the pressure-sensitive adhesive is used in view of the above problems.

[0007]

As a result of intensive studies for solving the above-mentioned problems, the present invention has revealed that when applying a heat-sensitive adhesive, the contact angle of the foam sheet is 70 degrees or more and 105 degrees or less. That is, it has been found that a uniform coating film can be formed even by one coating, which has led to the completion of the present invention. At least one surface of the foam sheet is non-adhesive at room temperature, but is heated. A foam sheet having a heat-sensitive adhesive layer formed by providing a heat-sensitive adhesive that exhibits adhesiveness by maintaining the adhesiveness for a long period of time,
The foam sheet has a contact angle of 70 degrees or more and 105 degrees or less. A sheet-like material may be laminated as a reinforcing material on the foam sheet.

Further, in the method for producing a foam sheet having a heat-sensitive adhesive layer of the present invention, the substrate has a contact angle of 70 degrees or more.
A foam sheet having a temperature of 05 degrees or less, which is non-adhesive at room temperature, but develops adhesiveness by heating, and the adhesiveness continues for a long period of time thereafter. Is a water-dispersed emulsion, which is applied onto at least one surface of the foam sheet.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention.

In the figure, 1 is a foam sheet and 2 is a heat-sensitive adhesive layer. The foam sheet 1 is manufactured by slicing a foam block into a thin sheet or foaming it into a thin sheet. As this foam, EP
Examples include synthetic rubbers such as DM rubber, chloroprene rubber and ethylene propylene rubber, olefinic foams such as polypropylene, ethylene vinyl acetate and polyvinyl chloride, and flexible foams such as urethane foams.
It may be a closed cell or an open cell.

The foam sheet 1 has a contact angle of 70 degrees or more and 105 degrees or less, preferably 85 degrees or more and 100 degrees or less. When the contact angle is less than 70 degrees, the heat-sensitive adhesive is a water-dispersed emulsion, so that even if it is applied to the foam sheet 1, it is quickly absorbed by the foam or enters the cell quickly. The reason is that the coating film cannot be formed or the coating film becomes uneven, so that a uniform coating film cannot be formed. When the contact angle exceeds 105 degrees, the water-dispersible heat-sensitive adhesive cannot be applied to the foam sheet 1 to form a uniform coating film due to the cissing phenomenon. However, the formation of a coating film is improved by applying a surface treatment to reduce the contact angle.
Here, the "contact angle" means that a foam sheet having a thickness of 10 mm is sandwiched between aluminum foils, and the temperature is 180 to 200 ° C and the pressure is 4
It is a value (hereinafter, the same) measured by a contact angle meter, which was formed into a film by pressing at 0 to 50 Kg / cm ² for 60 seconds to 180 seconds.

The water absorption rate of the foam sheet 1 is preferably 1 minute or longer, more preferably 15 minutes or longer. This is because if the water absorption rate is as short as less than 1 minute, the coated heat-sensitive adhesive will be absorbed before the coating film is formed and the coating film cannot be formed. Here, the "water absorption rate" is a value (hereinafter, the same) obtained by using a microsyringe on a foam sheet, dropping 0.015 ml of a water drop, and measuring the time taken for the water drop to be absorbed.

When the foam sheet 1 is a foam having a self-skin, the cells do not appear on the surface to be coated, so that the uniform and smooth heat-sensitive adhesive layer 2 can be easily formed by coating. Therefore, in order to form a uniform coating film, the foam sheet 1 is a foam having a self-skin and a contact angle of 7
0 degrees or more and 105 degrees or less (particularly preferably 85 degrees or more and 10 degrees or less)
It is particularly preferable that the water absorption rate is 0 degree or less) and the water absorption rate is 1 minute or more (particularly preferably 15 minutes or more). If the contact angle is 70 degrees or more, the water absorption rate is 1 minute or more.

Further, the foam sheet 1 is suitable for forming a uniform coating film when the cell diameter of the foam is as large as 900 μm or more because the coated heat-sensitive adhesive is absorbed or easily falls into the cell. Absent. Therefore, the cell diameter is less than 900 μm, preferably 600 μm or less, particularly preferably 200 μm.
μm or less is preferable. Here, the "cell diameter" is a value (hereinafter, the same) obtained by measuring the average cell diameter on a surface sliced perpendicularly to the foaming direction of the foam. The method uses a 70x microscope, counts the number of cells present in 0.1 square inch,
From this, the average cell diameter (μm / cell) is obtained.
Therefore, the most preferable foam sheet has a cell diameter of 900 μm or less (preferably 600 μm or less) under the above conditions.

In particular, in order to improve waterproofness, the contact angle 9
Air permeability at 0 degrees or more and 10 mm thickness is 10 cc /
An example of the waterproof urethane foam sheet is cm ² / sec or less.

Further, the heat-sensitive adhesive of the heat-sensitive adhesive layer 2 has a basic composition of a thermoplastic resin, a tackifier and a solid plasticizer and is non-adhesive at room temperature, but becomes sticky by heating. It develops and the stickiness continues for a long time after that. The heat-sensitive adhesive may be a conventionally known one, for example, as described in "Adhesion Handbook" (12th edition, Showa 55, Kobunshi Kogyo Kai), the heat-sensitive delayed tack adhesive. This heat-sensitive adhesive adjusts the glass transition point of the thermoplastic resin, the tackifier, and the softening point of the solid plasticizer to control the temperature at which the adhesiveness is exhibited by heating. The heat-sensitive adhesive needs to exhibit adhesiveness at a temperature lower than the melting point of the foam sheet 1, but since the foam has a different melting point depending on the material used, the temperature is adjusted as described above. Usually, the tackiness is developed at 70 ° C. to 110 ° C., but it can be made to appear at a temperature lower or higher. Further, the heat-sensitive adhesive can be improved by appropriately adding inorganic fillers, natural and synthetic waxes, liquid plasticizers, dispersants, defoamers, thickeners, etc. to the above basic composition. .

FIG. 2 is a perspective view showing another embodiment of the present invention. The same components as those of the above embodiment are designated by the same reference numerals and detailed description thereof will be omitted. In this example, the sheet-like material 3 is provided as a reinforcing material, and the others are the same as those in the above-described embodiment. Since the foam sheet 1 is formed of foam and has a sheet shape, it has no rigidity and is soft. Therefore, the shape of the foam sheet 1 is not stable when attached to an adherend, and the attachment is difficult and the workability is low. Poor, and excessive expansion and contraction also occur in the manufacturing process, and it is difficult to control tension, resulting in reduced productivity. For this reason, the sheet-like material 3 gives rigidity to the foam sheet 1 as a reinforcing material. The sheet-like material 3 is selected in consideration of this point. For example, the sheet-like material 3 may be a plastic film, paper, cloth or non-woven fabric.

For laminating the sheet-like material 3 on the foam sheet 1, any conventionally known means can be adopted. For example, a method of adhering it to the foam sheet 1 with an adhesive, integrating it at the time of molding the foam, or adhering with the adhesive when applying the heat-sensitive adhesive can be exemplified. Also, the sheet-like material 3
The position of is not limited to the embodiment shown in FIG. 2, and an appropriate position can be selected.

Next, a method of manufacturing the foam sheet having the heat-sensitive adhesive layer shown in FIG. 1 will be described with reference to FIG. First, a foam sheet 1 having a contact angle of 70 degrees or more and 105 degrees or less as shown in FIG. 3A and a heat-sensitive adhesive are prepared as a water-dispersed emulsion. The foam sheet 1 can be manufactured by slicing a foam block into a thin sheet or by foaming a thin sheet. Next, as shown in FIG. 3 (b), one surface of the foam sheet 1 is coated with a heat-sensitive adhesive, which is an aqueous dispersion type emulsion, by the coating device 4,
Dry to form the heat-sensitive adhesive layer 2. This coating may be a known method and is not particularly limited. Examples of the coating device (coating machine) 4 include a gravure coater, a roll coater, a die coater, a lip coater, and a spray coater. In particular, the foam sheet 1 has a contact angle of 7
When it is 0 ° or more and 105 ° or less, a uniform coating film can be formed by one coating, which improves work efficiency and is practical. Even when the foam sheet 1 deviates from the preferable range as described above, there are some foams in which a coating film can be formed by repeating coating several times or improving the pressure-sensitive adhesive. Not practical in terms of efficiency or economy. In addition,
In this production, a continuous foam sheet or a large foam sheet is used, a heat-sensitive adhesive is applied to it, dried, and then cut into a predetermined shape and size to obtain a predetermined shape. You may make it obtain the foam sheet which has a heat-sensitive adhesive layer.

Hereinafter, examples and comparative examples in which the material and characteristics of the foam sheet are changed are shown, and the test results are shown in Table 1. The structure of the foam sheet having the heat-sensitive adhesive layer is shown in FIG. 1, and the heat-sensitive adhesive layer is made by Toa Gosei Co., Ltd., Aron Tuck milky white water emulsion, TT.
-1226 was used. It had a solid content of 45 ± 1%, a viscosity of 3000 to 5000 mPas, and a PH of 7 to 8. This heat-sensitive adhesive was applied in a thickness of 200 μm and dried in hot air at 70 ° C. for 10 minutes, and then heat-activated for 1 minute on a 140 ° C. hot plate to develop heat-adhesiveness. .

[0021]

[Table 1]

The foam sheets of Examples and Comparative Examples shown in Table 1 are as follows. Pu (1) Polyester urethane foam Pu (2) Polyether urethane foam Pu (3) Polyale urethane foam Pu (4) Waterproof polyether urethane foam Pu (5) Polyether urethane foam Pu (6) Polyester urethane foam EPDM Ethylene propylene copolymer rubber foam PP (1) Polypropylene foam PP (2) PP (1) adhesive coated surface is corona treated

The test methods for the examples and comparative examples shown in Table 1 are as follows. (1) Contact angle A foam sheet having a thickness of 10 mm is sandwiched between aluminum foils, and the temperature is 180 to 200 ° C. and the pressure is 40 to 50.
The film was pressed at Kg / cm ² for 60 to 180 seconds and measured into a film with a contact angle meter. As the contact angle meter, Kyowa contact angle meter CA-A (Kyowa Scientific Co., Ltd.) was used. . (2) Water Absorption Rate Using a microsyringe on the foam sheet, 0.015 ml of water droplets was dripped and the time taken for the water droplets to be absorbed was measured. (3) Cell diameter The average cell diameter is measured on the surface sliced perpendicular to the foaming direction of the foam sheet. Specifically, the number of cells existing in 0.1 square inch is measured using a 70 × microscope. The average cell diameter (μm / cell) was obtained by counting. (4) Air permeability The woven fabric air permeability tester uses the Flangedle method, and the foam sheet thickness was measured in accordance with JIS L1004 with a thickness of 10 mm. It was used. (5) Formability of heat-sensitive adhesive layer One in which the heat-sensitive adhesive layer was applied to one surface of the foam sheet once and dried with warm air, and the formability of the adhesive layer was judged according to the criteria of ○ △ ×. Is.
◯: A uniform coating film is formed Δ: A coating film is formed ×: A coating film cannot be formed (6) Adhesive strength According to JIS K6848, the adhesive strength was measured by peeling at 90 degrees. After the layer surface was heated to develop tackiness, the stainless steel plate was reciprocated by a 2 kg roll (speed: 300 mm / mi).
n), and after 20 minutes, pulling speed 300 mm / mi
The 90 degree peel test was performed with n to measure the initial adhesive strength.

The test results shown in Table 1 show that
The foam sheet has a contact angle of 75 degrees and a cell diameter of 480 μm.
And the foam sheet of Example 2 has a contact angle of 81 degrees,
The cell diameter is 600 μm, and each is heat-sensitive with one coating.
A uniform coating film of the hydrophilic adhesive was formed. Foam of Example 3
The sheet has a contact angle of 97 degrees and a cell diameter of 170
The foam sheet of Example 4 had the same self-skin as Example 3.
Foam with a heat-sensitive adhesive on the skin
In both cases, a uniform coating film was formed with a single coating.
In the case of Example 4 having a skin surface on the surface, the uniformity is improved.
Also, the adhesive strength was improved. Also, according to the third and fourth embodiments.
Sea urchin has a contact angle of 95 degrees and an air permeability of 2 cc / cm ^Two/ Sec
Therefore, the waterproof property is also improved. Example 5 is EPDM foam
Body sheet, contact angle 97 degrees, cell diameter 700, once
A uniform coating film of the heat-sensitive adhesive could be formed by the above coating. Implementation
The foam sheet of Example 6 has a contact angle of 83 degrees and a cell diameter of 850.
Yes, a coating film can be formed, but the coating film formability and uniformity are poor.
Was there. This is because the cell diameter has increased. Implementation
The foam sheet of Example 7 had corona coated on the coated surface of the heat-sensitive adhesive.
The contact angle has been lowered by applying a treatment.
90 degree angle, cell diameter 280, uniform coating of heat-sensitive adhesive
A film could be formed.

Next, the foam sheet of Comparative Example 1 had a contact angle of 56 degrees and a cell diameter of 375, and the foam sheet of Comparative Example 2 had a contact angle of 67 degrees and a cell diameter of 190. ,
Due to the absorption of the heat-sensitive adhesive, the coatability was inferior in a single coating, and it could not be used. The foam sheet of Comparative Example 3 had a contact angle of 106 degrees and a cell diameter of 2
It was 80, and due to the cissing phenomenon of the heat-sensitive adhesive, the coating film formation was inferior and could not be allowed for use. From this, it can be understood that if the cell diameter of the foam sheet is extremely large, it has an influence on the coating film formation, but the contact angle has the largest influence.

[0026]

As described in detail above, the foam sheet having the heat-sensitive adhesive layer of the present invention is non-adhesive at room temperature on at least one side of the foam sheet, but becomes sticky by heating. Which is a foam sheet having a heat-sensitive adhesive layer formed by applying a heat-sensitive adhesive that exhibits long-term adhesiveness, and the foam sheet has a contact angle of 70 degrees or more and 105 degrees or less. Therefore, the following effects are achieved.

(1) Even in the case of a foam sheet, since a uniform coating film of the heat-sensitive adhesive is formed, the adhesive is developed over the entire coated surface and the adhesive strength is improved. (2) Since it is a heat-sensitive adhesive layer, a release paper covering this pressure-sensitive adhesive layer is not required, which saves resources and does not cause a problem of disposing of the release paper after use.

(3) Further, if a sheet-like material is attached to the foam sheet as a reinforcing material, in addition to the above-mentioned effects, tension control and the like can be easily performed even on a thin material or a foam sheet having large expansion and contraction, which enables production. And the productivity is improved. Also, the foam sheet itself has high shape retention,
The work of attaching to the adherend is facilitated and the workability is improved.

(4) Further, according to the manufacturing method of the present invention, a uniform coating film of the heat-sensitive adhesive can be formed by one coating, so that the working efficiency is good and the economical efficiency is also good.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a perspective view illustrating a manufacturing method of the present invention,
The process order is shown in (a) and (b).

[Explanation of symbols]

1 foam sheet 2 Thermosensitive adhesive layer 3 sheets 4 coating equipment

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[Procedure amendment]

[Submission date] February 7, 2003 (2003.2.7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (3)

[Claims] 1. A heat-sensitive adhesive that is non-adhesive at room temperature, develops adhesiveness by heating, and continues to remain adhesive for a long period of time after that is applied to at least one surface of the foam sheet. A foam sheet having a heat-sensitive adhesive layer, wherein the foam sheet has a contact angle of 70 degrees or more and 105 degrees or less. 2. The sheet-shaped material is laminated as a reinforcing material in a suitable place of the foam sheet.
A foam sheet having the heat-sensitive adhesive layer as described. 3. The base material is a foam sheet having a contact angle of 70 degrees or more and 105 degrees or less, and the adhesive has a basic composition of a thermoplastic resin, a solid plasticizer and a tackifier, and is non-adhesive at room temperature. , A thermosensitive adhesive that develops adhesiveness by heating, and that the adhesiveness continues for a long period of time after that, wherein the thermosensitive adhesive is a water-dispersed emulsion, which is applied to at least one surface of the foam sheet. A method for producing a foam sheet having a heat-sensitive adhesive layer, which comprises coating.