JPH01178575A - Double-side adhesive tape for pvc - Google Patents

Abstract

PURPOSE:To obtain the title tape which maintains excellent resistance to plasticizers even in long-term storage under high-temperature and high-humidity conditions, by forming a specified pressure-sensitive adhesive layer on both sides of a thin base sheet and providing a release paper at least on one side thereof. CONSTITUTION:A pressure-sensitive adhesive (A) is prepared by mixing an acrylic polymer (a) of the formula (wherein R1 is H or CH3; R2 is 1-18C alkyl) which comprises a homopolymer or copolymer of a monomer consisting mainly of alkyl (meth)acrylate and contains 15wt.% or less low-molecular-weight component having a molecular weight [by gel permeation chromatography (GPC)] of 100,000 or lower and 10wt.% or more high-molecular-weight component having a molecular weight (by GPC) of 1,000,000 or higher, if required, with a crosslinking agent (b). The title tape is obtained either by forming a 30-100mum thick layer of component A on both sides of a 10-1,000mum thin base sheet (B) and thereafter providing a release paper (C) at least on one side thereof to give an adhesive tape with a base material, or by forming the layer of component A on component C to give an adhesive tape without a base material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a double-sided adhesive tape for PVC that is applied to PVC products made of polyvinyl chloride sheets, films, and other molded products.

[Conventional technology]

Double-sided adhesive tapes using acrylic pressure-sensitive adhesives with excellent heat resistance and weather resistance are widely used for bonding PVC products together or bonding PVC products to other adherends. This double-sided adhesive tape includes an adhesive tape with a base material, which has a layer of acrylic pressure-sensitive adhesive on both sides of a thin base material and a release paper on at least one side, and a layer of pressure-sensitive adhesive on the release paper. Base material-less adhesive tapes are known, and are used as appropriate depending on the purpose of adhering PVC products. It goes without saying that in any of the above adhesive tapes, the release paper is peeled off and removed during use.

By the way, in PVC products, since polyvinyl chloride is a very hard polymer, various known plasticizers such as dioctyl phthalate and dibutyl adipate are often added to the product in order to improve its moldability and intended use. There are, but
When the double-sided adhesive tape described above is applied to a PVC product containing such a plasticizer, there is a drawback that the plasticizer easily migrates into the adhesive layer and the adhesive strength is extremely impaired.

For this reason, efforts have been made to date to improve the PVC products themselves, such as selecting plasticizers to be added to PVC that are less likely to transfer to the adhesive layer, and improving the acrylic polymer monomers that make up the adhesive layer. Various improvements have been attempted, such as modifying the properties of double-sided adhesive tapes by changing the composition and the composition of various compounding agents.

[Problem that the invention seeks to solve]

However, despite the above-mentioned attempts, almost no effective method has been found that can reliably prevent the decrease in adhesive strength caused by the migration of plasticizer into the adhesive layer. For this reason, after applying double-sided acrylic adhesive tape to PVC products, there is a significant decrease in adhesive strength during long-term storage, especially under high temperature and high humidity, and the PVC products are subject to their own weight or external pressure. However, there were disadvantages such as displacement and peeling of the adhesive part when the adhesive was used.

Therefore, the present invention solves the above-mentioned conventional problems, and provides a plastic-resistant product that does not show any decrease in adhesive strength due to plasticizer migration even after being stored at high temperature and high humidity for a long period of time after being applied to PVC products. The purpose is to provide a double-sided adhesive tape for PVC with excellent adhesive properties.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors discovered an acrylic polymer with a specific molecular weight structure that had not been previously used as the main adhesive component of acrylic pressure-sensitive adhesives. When used, a double-sided adhesive tape with excellent plasticizer resistance is obtained, and when used for bonding PVC products, adhesive strength due to plasticizer migration when stored at high temperatures for long periods of time is obtained. They found that it was possible to significantly suppress the decline in the amount of carbon dioxide, and completed this invention.

That is, the present invention provides an adhesive tape with a base material, in which a layer of pressure-sensitive adhesive is provided on both sides of a thin base material, and a release paper is provided on at least one side of the adhesive tape, or a layer of pressure-sensitive adhesive is provided on the release paper. In the double-sided adhesive tape for PVC, which is a base material-less adhesive tape, the above-mentioned pressure-sensitive adhesive has the following general formula; A molecular weight of 100,000 as measured by gel permeation chromatography, consisting of a 7-mer homopolymer or copolymer mainly composed of (meth)acrylic acid alkyl ester represented by ~18 alkyl groups) The present invention relates to a double-sided adhesive tape for vinyl chloride characterized by containing an acrylic polymer in which the following low molecular weight components are 15% by weight or less and high molecular weight components having a molecular weight of 1 million or more are 10% by weight or more.

As described above, in this invention, the acrylic polymer that is the main adhesive component contains a low molecular weight component of 100,000 or less, which is less than 15% by weight, and has a molecular weight of 100,000 or less.
By using a product with a specific molecular weight composition in which the high molecular weight component is 10% or more by weight, it is possible to greatly suppress the decrease in adhesive strength caused by the migration of plasticizers in the PVC product. An outstanding effect has been achieved in that even when an external pressing force is applied, displacement and peeling of the bonded portion can be avoided.

The reason why such an effect can be achieved is not necessarily clear, but it is assumed as follows.

In other words, when the low molecular weight components are reduced and the high molecular weight components are increased as in the present invention, although this does not necessarily inhibit the migration of the plasticizer in the PVC product to the adhesive layer, it does reduce the amount of migration. The adverse effect of plasticizers on adhesive properties is reduced; in other words, by having the above-mentioned molecular weight structure, the initial adhesion and cohesive force of the adhesive itself are improved, which reduces the residual stress after adhesion and the stress that occurs thereafter. This is probably due to the fact that it provides excellent residual stress resistance and durability.

On the other hand, the conventional wisdom regarding acrylic pressure-sensitive adhesives is that acrylic pressure-sensitive adhesives with a wide molecular weight distribution that contain a considerable amount of low molecular weight components are preferable in terms of achieving both initial adhesive strength and cohesive strength. Double-sided adhesive tapes using such adhesives have also been used for PVC products, but in this case, as mentioned above, after long-term storage at high temperatures and high humidity, the adhesive strength deteriorated significantly. It is.

In addition, in this specification, the molecular weight 1 measured by gel permeation chromatography method (hereinafter referred to as GPC method) in an uncrosslinked acrylic polymer
The weight percentage of low molecular weight components with a molecular weight of 0,000 or less (hereinafter referred to as low molecular weight component A) and the weight percentage of high molecular weight components with a molecular weight of 1 million or more (hereinafter referred to as high molecular weight component A)
2), and the weight percentage of low molecular weight components with a molecular weight of 100,000 or less (hereinafter referred to as low molecular weight percentage A'1) measured by the same method as above in the acrylic polymer after crosslinking, are both as follows. It is measured and calculated using a method.

That is, the dried sample polymer was packed with numerous holes (diameter 0.2
The weight percentage of the soluble polymer eluted in ethyl acetate (hereinafter referred to as percentage
) is measured.

Next, when the dried sample polymer is an uncrosslinked acrylic polymer, GPC using the above-mentioned soluble polymer is performed.
The weight percentage of low molecular weight components with a molecular weight of 100,000 or less (hereinafter referred to as percentage Y1) and the weight percentage of high molecular weight components with a molecular weight of 1 million or more (hereinafter referred to as percentage Y2) are determined from the molecular weight weight distribution curve by the method. When the dry sample polymer is an acrylic polymer after crosslinking, the weight percentage of low molecular weight components with a molecular weight of 100,000 or less (hereinafter, this is (referred to as percentage Y3) is measured. These percentages X, Y,.

From Yz, Y's, the low molecular weight percentage A1. The high molecular weight percentage A2 and the low molecular weight percentage are calculated according to the following formulas.

First, when the dry sample polymer is an uncrosslinked acrylic polymer, it is calculated as follows. In this case, most of the uncrosslinked acrylic polymers are soluble polymers, that is, the percentage is X#100, so the low molecular weight percentage A1 and the high molecular weight percentage A2 are the percentage Y, which is the actual value measured by GPC method, respectively. , Y2.

Moreover, when the dry sample polymer is an acrylic polymer after crosslinking, it is calculated as follows. Here, the acrylic polymer after crosslinking usually includes a crosslinked polymer and an uncrosslinked polymer, and the latter uncrosslinked polymer is mostly a soluble polymer, while the former crosslinked polymer has a degree of crosslinking. Depending on the molecular weight structure before crosslinking, etc., it can become a soluble polymer, an insoluble polymer, or even a mixed polymer of these. In other words, since the weight percentage X of the soluble polymer takes various values depending on the above-mentioned embodiments, the low molecular weight percentage A'+ does not necessarily match the percentage Y, which is the actual value measured by the GPC method, and the amount of insoluble polymer is small. However, if it exists, it will be smaller than the above percentage Y3.

The conditions for measuring the molecular weight distribution curve using the above GPC method are as follows: Sample concentration: 1/ml, Sample groove depth: 5
00■, column temperature 40°C, flow rate 1.0ml) min.

[Structure and operation of the invention]

Represented by the above general formula used in this invention (
As the meth)acrylic acid alkyl ester, R in the formula
Various acrylic acid alkyl esters or methacrylic acid alkyl esters in which 2 is an alkyl group having 1 to 18 carbon atoms can be used, and specifically, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 -ethylhexyl, octyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
Examples include octyl methacrylate.

Such (meth)acrylic acid alkyl ester may be used alone, or may be used in combination with other monomers copolymerizable with this as a main component. Other monomers include vinyl acetate, styrene, acrylonitrile,
Any of various monomers known as monomers for modifying acrylic pressure-sensitive adhesives, such as acrylamide, acrylic acid, methacrylic acid, hydroxyethyl acrylate, and glycidyl methacrylate, can be used.

From the viewpoint of adhesive properties, it is desirable that these other monomers be contained in an amount of 50% by weight or less based on the total amount of the alkyl (meth)acrylate.

The acrylic polymer used as the main adhesive component in this invention is a homopolymer or copolymer of the above-mentioned monomers containing (meth)acrylic acid alkyl ester as a main component, and has a molecular weight of lO as measured by GPC method.
15% by weight or less of low molecular weight components with a molecular weight of 1,000,000 or less, that is, the above-mentioned low molecular weight percentage AI is 15% or less, preferably 10% or less, and 10% by weight of high molecular weight components with a molecular weight of 1,000,000 or more.
In other words, it has a specific molecular weight structure characterized in that the polymer percentage A2 is 10% or more, preferably 15 to 70%.

If the above-mentioned low molecular weight percentage A exceeds 15% or high molecular weight percentage A2 is less than 10%, even if various additives for adjusting adhesive properties such as tackifying resins and crosslinking agents are blended, the plasticity It becomes difficult to suppress a decrease in adhesive strength due to migration of the agent. Note that if the polymer percentage A2 becomes too large, there is a risk that the initial adhesion strength will decrease, so as mentioned above, it is preferably up to about 70%.

The average molecular weight of the entire polymer in an acrylic polymer with such a specific molecular weight structure is not particularly specified, but the weight average molecular weight measured by the GPC method is usually 500,000 to 3,000,000. It is appropriate that it be within the range of .

In this invention, the acrylic polymer having the above molecular weight structure can be produced by various polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, etc. using the above monomers with polymerization catalysts such as azo compounds and peroxides. After polymerization using a polymerization method, an organic solvent that can dissolve only low molecular weight components is added to the polymerization solution to separate and remove the above components, or a method in which the above polymerization solution or the necessary compounding agents are added to it. It can be easily obtained by forming into a tape or the like, and then treating it with the same organic solvent as described above to elute low molecular weight components.

Furthermore, in solution polymerization, for example, a polymer with a small chain transfer coefficient such as benzene-methyl acetate or tent-butyl alcohol is used as a polymerization solvent, and the monomer concentration is increased and polymerization is carried out at as low a temperature as possible. It is also possible to obtain the acrylic polymer having the above-mentioned molecular weight structure of the present invention by selecting the operating conditions at the time, and further by selecting such polymerization operating conditions and removing the low-molecular-weight components after the polymerization. It is also an effective method to combine these operations as appropriate.

In the pressure-sensitive adhesive of the present invention, in addition to using the above-mentioned acrylic polymer as the main adhesive component, a tackifying resin that is commonly used for the purpose of adjusting adhesive properties may also be blended, and this tackifying resin In order to maintain heat resistance, it is preferable to select and use, for example, those having a softening point of 100° C. or higher from among terpene phenols, xylene resins, and the like. As additives other than the tackifier resin, various known additives such as plasticizers, fillers such as calcium carbonate and finely powdered silica, colorants, and ultraviolet absorbers can also be blended. Any of these additives may be used in the usual amounts applied to acrylic pressure-sensitive adhesives.

Further, the pressure sensitive adhesive of this invention can contain a crosslinking agent,
If the above-mentioned acrylic polymer is crosslinked with this crosslinking agent, the cohesive force as an adhesive can be further increased. A photocrosslinkable compound such as methylene bisacrylamide may be blended and photocrosslinked, and in this case, the same effect as described above can be achieved.In addition to crosslinking using these crosslinking agents and photocrosslinking, electron beam irradiation, etc. The same effect as above can also be obtained by employing other crosslinking means.

In the crosslinking using the above-mentioned crosslinking agent, the crosslinking agent used here includes a wide range of conventionally known crosslinking agents, but among these, polyfunctional melamine compounds and/or polyfunctional epoxy compounds, such as methylated trimethylol melamine, butyl Hexamethylol melamine, diglycidyl aniline, glycerin diglycidyl ether, and the like are particularly preferred as crosslinking agents in this invention. The amount used is 0 parts by weight per 100 parts by weight of the acrylic polymer.
．． 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight.

It is also preferable to use polyfunctional isocyanate compounds, and examples of such compounds include tolylene diisocyanate, hexamethylene diisocyanate, polymethylene polyphenylisocyanate, diphenylmethane diisocyanate, a dimer of diphenylmethane diisocyanate, and trimethylolpropane and tolylene diisocyanate. Examples include reaction products with isocyanates, reaction products between trimethylolpropane and hexamethylene diisocyanate, polyether polyisocyanates, and polyester polyisocyanates. Among these, especially 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate.
Most preferred are reaction products with moles. The amount of these compounds to be used is preferably in the range of 0.01 to 20 parts by weight, preferably 0.05 to 15 parts by weight, based on 100 parts by weight of the acrylic polymer.

In this invention, a pressure-sensitive adhesive such as the one described above is used, for example, by applying and drying the solution type on a release paper that has been subjected to a release treatment on paper or a plastic sheet, and then forming a film with a sensitivity of usually about 30 to 100 μm. By forming a pressure adhesive layer, it can be used as a base material-less adhesive tape.
In addition, the layer of the above-mentioned pressure-sensitive adhesive is usually made of paper, non-woven fabric, plastic sheet, metal foil, foam sheet, etc. with a thickness of 10 mm.
~1. It may be used as an adhesive tape with a base material by laminating it on both sides of a thin base material with a thickness of about O' 00 μm.

When manufacturing these tapes, it is preferable to appropriately crosslink the acrylic polymer constituting the adhesive layer through a coating and drying process and a light irradiation or electron beam irradiation process after this process. Then, if the low molecular weight component with a molecular weight of 100,000 or less measured by GPC method in the acrylic polymer after crosslinking is made to be IO weight percent or less in the total polymer, that is, the low molecular weight percentage A+ mentioned above is 10% or less. , more favorable results can be obtained in preventing a decrease in adhesive strength caused by migration of plasticizers in PVC products.

The double-sided adhesive tape for PVC of the present invention is made of the above-mentioned adhesive tape without a base material or an adhesive tape with a base material, and is used for adhesion of PVC products to each other or for adhesion of PVC products to other adherends. By using this adhesive, it is possible to exhibit stable adhesive strength over a long period of time.

〔Effect of the invention〕

As described above, in this invention, as the acrylic polymer constituting the pressure-sensitive adhesive layer, an acrylic polymer having a specific molecular weight composition in which the low molecular weight component and the high molecular weight component are in a specific amount is used. As a result, we have developed a double-sided adhesive tape for PVC with excellent plasticizer resistance that does not show any decrease in adhesive strength due to migration of plasticizers even after being applied to PVC products and stored for a long period of time under high salt and high humidity conditions. Obtainable.

〔Example〕

Next, examples of the present invention will be described in more detail. Note that hereinafter, parts mean parts by weight, and the acrylic polymer solutions P-1 to P-5 used in the following Examples and Comparative Examples were prepared by the following method.

Acrylic polymer solution pt> 80 parts of n-butyl acrylate, 15 parts of vinyl acetate, 5 parts of acrylic acid, and 100 parts of toluene as a polymerization solvent were put into a flask and heated for 2 hours while introducing nitrogen gas. Stirred. After removing oxygen from the polymerization system in this way, 0.02 part of azobisisobutyronitrile was added and the temperature was raised to 50°C. After 3 hours, 0.02 part of azobisisobutyronitrile and 50 parts of toluene were further added, and the polymerization reaction was continued for 3 parts. Then, 0.02 part of azobisisobutyronitrile was added again, and the temperature was increased to 65°C.
The polymerization reaction was continued for 5 hours by increasing the temperature to 4.
A 0% by weight acrylic polymer solution P-1 was obtained.

Acrylic polymer solution P-2> Add n- to 100 parts of the above acrylic polymer solution P-1.
120 parts of hebutane was added dropwise over 5 hours with stirring, and after standing still for 24 hours, the supernatant liquid was separated.

After that, the supernatant liquid was added to the separated polymer solution with toluene 6
After adding 0 parts and dissolving it, 120 parts of n-hebutane was added in the same manner as above and the supernatant liquid was separated for 3 more times.
Repeated times. After adding toluene som to the final polymer solution obtained in this manner, it was concentrated to obtain an acrylic polymer solution P-2 having a polymer concentration of 30% by weight.

<Acrylic polymer solution P-3> All the supernatant liquid separated during the preparation of the above acrylic polymer solution P-2 was collected, concentrated to a polymer concentration of 50% by weight, and this and the above An acrylic polymer solution P-2 was mixed with the acrylic polymer solution P-2 at a weight ratio of 1=9 to obtain an acrylic polymer solution P-3 having a polymer concentration of 32% by weight.

<Acrylic polymer solution P-4> All the supernatant liquid separated during the preparation of the above acrylic polymer solution P-2 was collected, concentrated to a polymer concentration of 50% by weight, and this and the above acrylic polymer solution Acrylic polymer solution P-5 is obtained by mixing with polymer solution P-2 at a weight ratio of 228 to obtain acrylic polymer solution P-4 with a concentration of 34% by weight.
Pour 50 parts of n-butyl acrylate, 50 parts of 2-ethylhexyl acrylate, 1 part of acrylic acid, and 200 parts of ethyl acetate as a polymerization solvent into a five-layer tube. An acrylic polymer solution was obtained in the same manner as above.

Next, 12 parts of methanol was added to 100 parts of this polymer solution.
0 part was added dropwise over 5 hours while stirring, and after standing still for 24 hours, the supernatant liquid was separated. Thereafter, 90 parts of toluene was added to the polymer solution from which the supernatant liquid had been separated, and 1'20 parts of methanol was added in the same manner as above to separate the supernatant liquid. The procedure was repeated 3 times. Add 1 portion of toluene to the final polymer solution obtained in this way.
After adding 50 parts, it was concentrated to a polymer concentration of 30 parts.
A acrylic polymer solution P-5 with % overload was obtained.

In addition, these a) acrylic polymer solutions P-1 to P-5
is the weight percentage of the 'soluble polymer' constituting each polymer (the above percentage X), the 'GPC' of this soluble polymer
The weight average molecular weight according to the law, the weight percentage of low molecular weight components with the same molecular weight of 100,000 or less (the above-mentioned low molecular weight percentage Al')' and the weight percentage of the high molecular weight components with a batch molecular weight of 1 million or more [the above-mentioned high The molecular percentage A had a molecular weight structure as shown in Table 1 below.
□ - Table 1 Example 1 A tackifying resin was added to the acrylic polymer solution P-2 at a ratio of 10 parts to 100 parts of the acrylic polymer [trade name: Sumilite Resin PR1603, manufactured by Jumin Duress ■.
A pressure-sensitive It was made into an adhesive solution.

This solution was cast on a polyethylene terephthalate film with a thickness of 50 μm onto a silicone-treated release paper so that the thickness after drying was 50 μm.
A layer of pressure sensitive adhesive was formed by heating and drying for 0 minutes. Next, apply a layer of the above pressure-sensitive adhesive to a thickness of 40 μm 2 tsubo 1
) A double-sided adhesive tape for PVC was prepared by laminating both sides of a 5 g/m nonwoven fabric.

Example 2 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1, except that acrylic polymer solution P-3 was used instead of acrylic polymer solution P-2, and this solution was used in Example A double-sided adhesive tape for PVC was produced in the same manner as in Example 1.

Example 3 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1, except that acrylic polymer solution P-5 was used instead of acrylic polymer solution P-2, and this solution was used in Examples. A double-sided adhesive tape for PVC was produced in the same manner as in Example 1.

Comparative Example 1 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1, except that acrylic polymer solution P-1 was used instead of acrylic polymer solution P-2, and this solution was used in Examples. A double-sided adhesive tape for PVC was produced in the same manner as in Example 1.

Comparative Example 2 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1, except that acrylic polymer solution P-4 was used instead of acrylic polymer solution P-2, and this solution was used in Example A double-sided adhesive tape for PVC was produced in the same manner as in Example 1.

In order to investigate the performance of the double-sided adhesive tape for PVC obtained in the above Examples and Comparative Examples, the following adhesion test was conducted.

<Adhesion test> Each adhesive tape (width 2ON, length 150u+) was lined with a polyethylene terephthalate film (7125μm), and then lined with a 0.3m thick polyvinyl chloride sheet (
Contains 30% by weight of dioctyl phthalate as a plasticizer)
pasted on, measurement temperature: 20°C, paper removal speed: 30
Peel adhesion strength was measured at the initial stage and after storage at 40° C. and 80% RH for one week under conditions of 0 wm/min.

The above test results were as shown in Table 2 below. For reference, the same table shows the weight percentage of the soluble polymer (the above percentage The percentage (the low molecular weight percentage A'1) is also written. Here, percentage
The measurement of the low molecular weight percentage is only for the acrylic polymer excluding the tackifying resin.

Table 2 From the results in Table 2 above, it is clear that the double-sided adhesive tape according to the present invention exhibits excellent storage properties with almost no decrease in adhesive strength due to plasticizer migration. .

Claims (3)

[Claims] (1) Adhesive tape with a base material, which has a layer of pressure-sensitive adhesive on both sides of a thin base material and a release paper on at least one side, or a base material with a layer of pressure-sensitive adhesive on the release paper. In the double-sided adhesive tape for PVC, which is made into a material-less adhesive tape, the above pressure-sensitive adhesive has the following general formula; ▲ There are mathematical formulas, chemical formulas, tables, etc. Molecular weight measured by gel permeation chromatography, consisting of a homopolymer or copolymer of a monomer containing an alkyl (meth)acrylic acid ester as a main component, which is an alkyl group having 1 to 18 carbon atoms. Low molecular weight components of 100,000 or less are 15
1. A double-sided adhesive tape for vinyl chloride, characterized in that it contains an acrylic polymer in which the amount of the high molecular weight component is 10% by weight or less and the molecular weight is 1 million or more. (2) A double-sided adhesive tape for PVC according to claim (1), which is formed by crosslinking an acrylic polymer. (3) Claim (2) states that the acrylic polymer after crosslinking contains a low molecular weight component having a molecular weight of 100,000 or less measured by gel permeation chromatography in an amount of 10% by weight or less based on the total polymer. Double-sided adhesive tape for PVC.