JPS6026436B2 - Adhesive tape or sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive tape or sheet in which an adhesive layer is firmly bonded to a polyolefin resin film base material. This publication relates to an improvement in which an undercoat layer containing an epoxy resin as a main component is used between a film base material and an adhesive layer in order to firmly bond the film base material and the adhesive layer.

Conventionally, the curing agent for epoxy resin was
As described in the publication, a polyamide with a similar low molecular weight is used, which is made by dilating polyamines such as tetraethylenebentamine, trisdimethylaminomethylphenol, or unsaturated resin acids and reacting them with ethylenediamine, etc. It has a high vapor pressure, and has the disadvantage that it generates steam that is harmful to health during the process of mixing it with epoxy resin as a primer, applying it to a large base film, and drying it at high temperatures.

In addition, the conventional undercoat mixture of epoxy resin and curing agent has a short delivery time, limits the production process, wastes a lot of undercoat, and the reacted solids stick to containers and piping. This had disadvantages such as hindering continuous production.

The object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an adhesive tape or sheet that does not generate vapor harmful to health, has a long primer coating time, and has an adhesive firmly bonded to a film base material. shall be.

The gist of the present invention is to combine an epoxy resin, at least one alkyl ester of acrylic acid or methacrylic acid, and a 2-dialkyl ester of acrylic acid or methacrylic acid on the surface of a polyolefin resin film whose surface has been oxidized. The present invention relates to an adhesive tape or sheet, characterized in that an acrylic adhesive layer is provided through an undercoat layer mainly composed of a copolymer with at least one of aminoethyl esters. The polyolefin resin film used in the present invention is preferably a film made of low-density polyethylene, high-density polyethylene, polypropylene, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 1% by weight or less, or a mixture thereof.

The surface of the film is subjected to oxidation treatment such as flame treatment, corona discharge, radiation irradiation, etc. in order to impart adhesive properties. In the present invention, an acrylic adhesive layer is provided on the surface of the polyolefin resin film, the surface of which has been oxidized, via an undercoat layer.

．． In the present invention, the undercoat layer consists of an epoxy resin, an alkyl ester of acrylic acid or methacrylic acid which is a curing agent for the epoxy resin, and a 2-dialkylaminoethyl ester of acrylic acid or methacrylic acid. The main component is a copolymer of

As the epoxy resin used in the present invention, those made by reacting bisphenol A and epichlorohydrin, epoxidized novolac resins, polyglycol type epoxy resins, etc. are suitable. Among the reacted epoxy resins, those with low viscosity are preferred because they have excellent adhesion to polyolefin resin films.

As the alkyl ester of acrylic acid or methacrylic acid used in the present invention, the alkyl group has 1 carbon number.
-8 esters are preferred, specifically acrylic acid n
-butyl, methyl methacrylate, ethyl acrylate,
2-ethylhexyl acrylate and the like are preferably used.
2 of acrylic acid or methacrylic acid used in the present invention
-Dialkylaminoethyl esters include those whose alkyl group has 1 or 2 carbon atoms, that is, 2-dimethylaminoethyl ester, 2-diethylaminoethyl ester, or 2-methylethylami/ethyl ester of acrylic acid or methacrylic acid. is suitable.

The undercoat layer used in the present invention is prepared by copolymerizing at least one of the alkyl esters of acrylic acid or methacrylic acid and at least one of the 2-dialkyl amide/ethyl esters of acrylic acid or methacrylic acid. The copolymerization ratio is preferably in the range of 30 to 60 parts by weight to 10 parts by weight of the former, and more preferably in the range of 40 to 55 parts by weight of the latter. It is better to

When the ratio of the latter is increased, the reactivity of the resulting copolymer as a curing agent increases, but its average degree of polymerization decreases, making it difficult to use as an undercoat.
If the latter ratio is decreased, the reactivity as a curing agent decreases, but the average degree of polymerization increases and the initial cohesive force of the undercoat layer increases. As a method for copolymerizing the above-mentioned two, heating polymerization may be carried out using a polymerization initiator such as azobisisobutyronitrile in a solvent such as ethyl acetate. The average degree of polymerization of this copolymer is preferably 5 or more from the viewpoint of volatility, and more preferably an average degree of polymerization of 10 to 100. This copolymer has a tertiary amine structure in the molecule,
While it acts as a curing agent for epoxy resins, it also does not function to crosslink epoxy resins together, and has strong adhesive properties itself. The mixing ratio of the epoxy resin and the copolymer as its curing agent is preferably in the range of 10 parts by weight for the former to 10 to 20 parts by weight for the latter.

. As the acrylic adhesive used in the present invention, solution type and emulsion type adhesives containing acrylic acid ester as the main raw material can be used, and in particular, acrylic acid ester having an alkyl group having 4 to 8 carbon atoms as the main monomer can be used. An adhesive is prepared by adding 2 to 7% by weight of monomers such as methyl methacrylate, acrylamide, methacrylic acid, and acrylic acid to this and polymerizing it, or further adding zinc,
Adhesives cross-linked with metal ions such as aluminum and magnesium, melamine resin, polyisocyanate, etc. are suitable. To provide a primer layer on a polyolefin resin film whose surface has been oxidized, each component of the primer described above is prepared as a 5-1% by weight solution in a solvent such as ethyl acetate, methyl ethyl ketone, or methyl isobutyl ketone. Just apply it.

To provide an acrylic adhesive layer on the applied undercoat layer, it is sufficient to apply and dry the above-mentioned emulsion type or solution type acrylic adhesive, especially when the undercoat layer is hardened. A type adhesive is preferred, and when the undercoat layer is semi-cured or hard-cured, not only an emulsion type but also a solution type adhesive is suitably used.

The undercoat used in the adhesive tape or sheet of the present invention consists of an epoxy resin, an alkyl ester of acrylic acid or acrylic acid, and a combination of acrylic acid or methacrylic acid.
- Since the main component is a copolymer with dialkylaminoethyl ester, it has adhesive properties even in the hardened state and adheres well to the base film, and the hydroxyl groups generated on the surface of the base film by oxidation treatment. A reactive group having equiactive hydrogen and an epoxy group etc. react to form a strong bond, and even after curing is completed, it remains flexible and does not cause cracking at the interface with the polyolefin resin film that is the base material.

It also has good molecular affinity with acrylic pressure-sensitive adhesives and is strongly bonded to them. Furthermore, since the copolymer that is the curing agent is a polymeric substance, it is difficult to react with the epoxy resin in a diluted solution state, and the delivery time is very long. therefore,
It has advantages in the manufacturing process, such as saving the trouble of replacing the solution, reducing waste of the solution, and preventing solid matter produced by the reaction from sticking to containers or piping and hindering continuous production. Furthermore, since a British polymer is used as a curing agent, it is non-volatile and there is no need to worry about the generation of vapors that are harmful to health. The adhesive tape or sheet of the present invention has an acrylic adhesive layer provided on an oxidized polyolefin resin film via an undercoat layer having the above-mentioned structure, so that the undercoat layer has strong adhesion. Due to its properties, the base material polyolefin resin film and the acrylic pressure-sensitive adhesive layer are firmly bonded to each other.

Since the adhesive tape or sheet of the present invention uses a primer layer mainly composed of an epoxy resin and a high molecular weight copolymer, it has low volatility and does not generate vapors that are harmful to health. , the production time is long, the production process is not limited, and there is no waste of primer, making it easy to manufacture.

The adhesive tape or sheet of the present invention can be suitably used for a wide range of applications such as surface protection, packaging, packaging, bundling, and repair.

The present invention will be explained in more detail with reference to Examples below.

Example 1 57.5 parts by weight of n-butyl acrylate, 7.5 parts by weight of 4-ethyl acrylate, 35 parts by weight of 2-dimethylaminoethyl methacrylate, 0.4 parts by weight of azobisisobutyronitrile
Part by weight was dissolved in 10 parts by weight of ethyl acetate, and the polymerization was completed by heating and refluxing to prepare a curing agent solution.

The curing agent solution had a viscosity of approximately 1000 centipoise and a solids concentration of 48.8%. The average degree of polymerization of the solid content of the copolymer was about 15. Next, one section of the biaxially stretched polypropylene film with a thickness of 60 microns was subjected to a corona discharge treatment, and the treated surface was coated with 5 parts by weight of liquid epoxy resin, 5 parts by weight of solid epoxy resin, and 10 parts by weight of the above-mentioned curing agent solution. An undercoat solution containing 1,675 parts by weight of methyl ethyl ketone and 1,675 parts by weight of methyl ethyl ketone was applied at a rate of 50 ta per coat, and dried with hot air at 8 pm for 300 seconds to completely evaporate the solvent. The primer layer remaining on the film surface is still hardly cured,
It was in a sticky state. On the primer layer in this state, 2 parts by weight of 2-ethylxyl acrylate, 65 parts by weight of n-butyl acrylate, 3 parts by weight of methyl methacrylate la, 3 parts by weight of acrylic acid, 0.4 parts by weight of sodium alkylbenzenesulfonate parts by weight, 0.7 parts by weight of polyoxyethylene alkyl ether, 0.7 parts by weight of potassium persulfate. 2 parts by weight of 28% ammonia water was added to an emulsion type acrylic adhesive with a solid content concentration of approximately 40% obtained by emulsion polymerization of 1 part by weight of a box, 0.1 part by weight of sodium bisulfite, and 15 parts by weight of water. This was applied at a rate of 50 ta per watt, and dried and cured for 10 minutes with hot air at 90°C to obtain a pressure-sensitive adhesive sheet with an adhesive thickness of about 20 microns.

Example 2 Immediately after preparing the primer solution in Example 1, 100 yen,
When placed in a beaker, covered with paper, and left in a 25 qo room for 3 days, there was a weight loss of about 12 quarts due to evaporation of the solvent, but there were no precipitates or other abnormalities in appearance.

A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that methyl ethyl ketone was replenished to the original weight and this primer solution was used. Example 3 As in Example 1, a primer layer was applied to the surface of a corona discharge-treated polypropylene film, and the primed film was left in a room at 20° C. for one day.

Although the surface of the undercoat layer was slightly cured, it still had tackiness. An acrylic adhesive layer was coated on this surface in exactly the same manner as in Example 1 to obtain an adhesive sheet. Example
4 A pressure-sensitive adhesive sheet was obtained in exactly the same manner as in Example 3, except that the number of days for shelf life of the film coated with the undercoat layer in Example 3 was changed to 5 days.

It should be noted that the surface of the undercoat layer after being left for 5 days had undergone considerable curing, and only slight tackiness remained. Example 5 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that the undercoat solution was left to stand for 3 days in the same manner as in Example 2.

Example 6, 7.8 Parts by weight of 2-ethylhexyl acrylate 2, acrylic acid n
- 65 parts by weight of butyl, 3 parts by weight of methyl methacrylate, 3 parts by weight of acrylic acid, and 0.1 part by weight of penzoyl peroxide were dissolved in 15 parts by weight of ethyl acetate, and the mixture was heated and refluxed to complete the polymerization. .

The resulting solution had a solid content concentration of 39%, which was adjusted to 35% by adding toluene to obtain a solution-type acrylic adhesive solution. One side of the 40-micron-thick low-density polyethylene film was then subjected to a corona discharge treatment, and three sheets of this treated film were prepared, and each treated surface was coated with the material used in Examples 3, 4, and 5, respectively. After applying and drying the same primer solution in exactly the same way and leaving it for the same number of days, apply the above solution type acrylic adhesive solution at 60 tons per coat, dry at 80q0 for 5 minutes, cure, and glue. An adhesive sheet of about 20 microns was obtained.

Examples 6 and 7 are arranged in the order corresponding to Examples 3, 4, and 5.
,8. Comparative Examples 1 to 8 Parts by weight of liquid epoxy resin 5, parts by weight of solid epoxy resin 5, parts by weight of polyamide type curing agent 5, and 1725 parts by weight of methyl ethyl ketone were mixed to prepare an undercoat solution.

Using this undercoat solution, eight adhesive sheets were obtained in the same manner as in Examples 1 to 8 except for the above. However, in the cases corresponding to Examples 2, 5, and 8, when the primer solution was left for 3 days, it hardened and could not be used, so the number of days it was left for 3 days was changed to 1 day. These are referred to as Comparative Examples 1 to 8 in the order corresponding to Examples 1 to 8. When measuring the adhesive physical properties of the 1-pin pupil adhesive sheets obtained as described above, it was found that Examples 1 to 5 and Comparative Examples 1 to 5 using emulsion-type acrylic adhesives had a width of 2 squares per pupil. Examples 6 to 8 in which the SP sheep holding power was about 200 mm, the tack was about 5, and a solution-type acrylic adhesive was used.
, Comparative Examples 6 to 8 all have an SP adhesive strength of about 2.
On the 40th evening, the tack was about 8.

The above SP adhesive strength refers to the 28% of stainless steel plate specified in JISR-62 for approximately 125 vertical ribs and approximately 5 gunwales.
This is the peeling force obtained when polishing in the vertical direction with water-resistant abrasive paper, attaching a sample tape in the same direction, and peeling off at 180 degrees at a speed of 30 seams/minute after 18 minutes. Tack is a value determined by the Dow falling ball test. Table 1 shows the results of testing the effectiveness of the primer on this adhesive sheet using the following peeling method and friction method.

For peel-off, adhere the adhesive sides of the same adhesive sheets together and press them together, leave them in an air bath at 70 pm for 1 hour, then take them out, fix one sheet on a flat table, and press the other sheet. was slowly peeled off at an angle of 18°, and whether or not peeling occurred between the Motomura film and the primer layer was scored on a 5-point scale.

In this case, peeling occurs between the base film and the undercoat layer. In the friction method, the adhesive sheet was placed on a flat desk surface with the adhesive side facing up, and rubbed with the tip of a finger, and the ease with which the adhesive fell off was scored on a 5-point scale.

In addition, according to this method, peeling between the undercoat layer and the adhesive layer is likely to occur. In both methods, the higher the score, the better the adhesion. From the results shown in Table 1 and above, the adhesive sheet of the present invention has a long release time for its undercoat solution, and the undercoat layer can be applied several days later before an acrylic adhesive layer is applied thereon. It can be seen that the base film and adhesive layer are strongly bonded under a wide range of usage conditions compared to conventional primers.

Claims (1)

[Scope of Claims] 1. An epoxy resin, at least one alkyl ester of acrylic acid or methacrylic acid, and a 2-dialkyl ester of acrylic acid or methacrylic acid are formed on the surface of a polyolefin resin film whose surface has been oxidized. An adhesive tape or sheet characterized in that an acrylic adhesive layer is provided through an undercoat layer mainly composed of a copolymer with at least one of aminoethyl esters. 2. A patent claim in which the alkyl group of the alkyl ester of acrylic acid or methacrylic acid has 1 to 8 carbon atoms, and the alkyl group of the 2-dialkylaminoethyl ester of acrylic acid or methacrylic acid has 1 or 2 carbon atoms. The adhesive tape or sheet according to item 1. 3. The adhesive tape or sheet according to claim 1 or 2, wherein the copolymer has an average degree of polymerization of 5 or more. 4. The adhesive tape according to claim 1, 2, or 3, wherein the undercoat layer contains the copolymer in a ratio of 10 to 200 parts by weight based on 100 parts by weight of the epoxy resin. Or a sheet.