JPH0722595B2 - Medical adhesive and medical patch using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a medical pressure-sensitive adhesive excellent in "familiarity" and adhesion to the skin and having a good balance of adhesiveness and cohesiveness, and this medical adhesive. The present invention relates to a medical patch using.

(Prior Art) Generally used as an adhesive or an adhesive base for an adhesive for commonly used patches, adhesive sheets, adhesive tapes, etc. for medical use, stationery, packaging, industrial use, etc. Has a second-order transition temperature (Tg) of -15 ℃ ~-
That is within the range of 73 ℃.

That is, as the second-order transition temperature is lower, a softer and more tacky pressure-sensitive adhesive (or a pressure-sensitive adhesive base, hereinafter including a pressure-sensitive adhesive base) can be obtained, but on the other hand, its cohesive force decreases, so Considering the balance between adhesiveness and cohesive strength,
It was considered that the pressure-sensitive adhesive having a glass transition temperature within the above range and having a second-order transition temperature outside this range could not be put to practical use in terms of adhesiveness and retentivity.

There are a wide range of (co) polymers as the chemical composition of conventional pressure sensitive adhesives, and various additives are also added to it, but especially the strength of the pressure sensitive adhesive, good aging resistance, and property modification In view of the balance of possibilities and the balance of cost, (meth) acrylic acid ester-based (co) polymers have become more important in recent years.
Since there is no or very little skin irritation, it has been favorably used for medical purposes.

On the other hand, in such a (meth) acrylic acid ester-based polymer, a (co) polymer consisting only of (meth) acrylic acid esters generally lacks cohesive force (as a phenomenon, the adhesive may stretch in a string form, Since there is a large tendency for glue migration due to the cohesive failure phenomenon), copolymerization of (meth) acrylic acid ester and / or (meth) acrylamide having a polar group in the side chain is carried out for the purpose of compensating for this property. Alternatively, it was necessary to increase the cohesive force to a predetermined level by post-crosslinking at the introduced polar groups. Among other things, like medical applications,
It is necessary to use an adhesive that is easier to stretch and soft in order to follow the vigorous movement of the skin, and its glass transition temperature is preferably as low as possible in the above range, so introduction of polar groups and post-crosslinking etc. It was necessary to do.

(Problems to be Solved by the Invention) For the purpose of compensating for the drawback caused by the cohesive failure phenomenon of the pressure-sensitive adhesive, it was also studied to increase the cohesive force by introducing a polar group into the polymer as described above. However, there is a drawback that the glass transition temperature rises again and the tackiness decreases.

As a means of maintaining flexibility at a relatively low glass transition temperature and maintaining a predetermined cohesive force, a small amount of a carboxyl group (-COOH) is introduced into the polymer (that is, the cohesive force is not obtained only by the polar effect of the carboxyl group). There is the idea that the portion is later cross-linked with another post-crosslinking agent, and the carboxyl group component therefor is acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride. Have been proposed or used.

The cross-linking agent in that case includes melamine cross-linking, isocyanate cross-linking, polyvalent metal ion cross-linking, epoxy cross-linking and the like, but in medical applications, polyvalent metal ion cross-linking has been emphasized from the viewpoint of skin irritation. However, even in that case, it is unavoidable that if the cohesive strength is improved to a necessary and sufficient place, the softness, the stickiness and the conformability to the skin are sacrificed again.

The present invention is to solve the above-mentioned conventional problems, and its purpose is to prevent cohesive failure because it has excellent cohesiveness and viscoelastic softness, and its cohesive strength is sufficiently maintained. An object of the present invention is to provide a medical pressure-sensitive adhesive that does not cause a stringing phenomenon or a migration phenomenon of the pressure-sensitive adhesive, and a medical patch prepared using the pressure-sensitive adhesive.

(Means for Solving Problems) The medical adhesive of the present invention is obtained by copolymerizing (A) 2-acryloyloxyethylsuccinic acid and (B) (meth) acrylic acid alkyl ester. And a copolymer having a second-order transition temperature of −15 ° C. to −73 ° C., which achieves the above object.

In the medical patch of the present invention, the pressure-sensitive adhesive layer containing the above-mentioned medical pressure-sensitive adhesive as a main component is provided on the surface of the flexible backing support, and thereby the above object is achieved.

The present invention will be described in detail below.

Essential constitution of the present invention The medical adhesive (including an adhesive base for medical purposes) of the present invention was obtained by copolymerizing the following components (A) and (B) as essential components. Contains a polymer. The second-order transition temperature (Tg) of this polymer was determined by the DSC method (JIS-K-7121-198).
The value measured according to 7) is in the range of -15 ° C to -73 ° C.

(A) component: 2-acryloyl-oxyethyl-succinic acid (B) component: acrylic acid ester, methacrylic acid ester or a mixture thereof (hereinafter referred to as (meth) acrylic acid ester) (A) and (B) both components The preferred quantitative ratio range of (A) component to (B) component is 0.5: 99.5 by weight ratio.
It is preferably within the range of 20 to 80.

Preferable weight (or number) average molecular weight of the polymer When measured by the GPC method, the weight average molecular weight of the polymer is preferably 200,000 or more (or 50,000 or more in number average molecular weight).

Motivation leading to the invention If the aim of the invention is to be realized within the scope of the prior art, a (meth) acrylic ester which gives a polymer with a Tg as low as possible is used as a main component and a small amount of acrylic acid is added thereto. , Methacrylic acid, itaconic acid, (anhydrous)
Copolymerize maleic acid, etc., and replace the carboxyl group
The most suitable means so far is to recover the insufficient cohesive strength by crosslinking with a polyfunctional (bifunctional or more) crosslinking agent, and among them, the carboxyl group-containing component is (meth) acrylic acid. It is the inventor's research experience that gives the best polymer.

However, as a result of analysis by the inventor of the unsatisfactory reason, it was found that (meth) acrylic acid (and the same in other cases) showed a cross-link between -COOH when it was copolymerized and incorporated in the polymer. It is assumed that the following drawbacks will occur.

(I) the side chain is an ester residue which is adjacent to the carboxyl group (e.g., alkyl group of C ₄ -C ₁₂₎ as a carboxyl group by steric hindrance of present just urban canyons, crosslinking agent from the later, The probability of being able to reach a close range that can react with the carboxyl group that is the reaction partner is very low, and even if there is something that reacts, it is not quantitative, but the number of incorporated carboxyl groups and / or added This results in up to a percentage of the cross-linking agent contributing to the reaction.

(Ii) The flexibility (= flexibility) of the carboxyl group cannot be obtained because the alkyl group is bonded to the main chain,
This also reduces the above-mentioned reaction probability of the carboxyl group (=
(Reduction of reactivity) is further promoted.

(Iii) Therefore, in order to obtain the required level of crosslinking agent, it is necessary to add much more than the theoretical amount of carboxyl groups and / or crosslinking agent. for that reason,
For example, when the amount of the carboxyl group is large, the flexibility is lowered and the Tg is increased by itself, and a large excess amount of the crosslinking agent has another effect.

(Iv) Even if the portion where the cross-linking is realized happens to be caught, for example, when the cross-linking agent is a polyvalent metal ion, a sufficient length to give flexibility to the cross-linking portion cannot be obtained, so that the cross-linking point is This results in a rigid structure, which in turn tends to reduce the flexibility and adhesiveness of the adhesive layer.

As a result of the insight of (i) to (iv) above, in order to improve the conventional drawbacks, the carboxyl group (-COOH) is not in a form directly linked to the main chain, but is a branch having several segments protruding from the main chain. It came to the assumption that it had to be attached to the tip of the. The degree of protrusion, that is, the number of segments in the middle, is better if it is said from such an idea, but it is estimated that it may be equivalent to C4 or more with a linear alkyl group chain length. Was given.

From the above motives and ideas of improvement, the present invention has been completed as described above (essential configuration).

That is, in the present invention, 2-acryloyl-oxyethyl-succinic acid, which is the above-mentioned component (A), is used as one carboxyl group-containing monomer satisfying the above conditions, and it has been discovered that the objective can be achieved thereby. I did.

Mechanism of action (i) Central mechanism of action The ideal is as described in the section of motivation. Here, in the component (A), a total of 6 carbon atoms and oxygen atoms are arranged in series between the ester bond (-COO-) and the terminal carboxyl group (-COOH), and the length thereof is Because of this, it has gained sufficient flexibility. And
This brings the following effects.

(A) The reactivity of the carboxyl group (-COOH) is greatly improved as compared with the case of (meth) acrylic acid, which was the mainstream in the past, and the number of the carboxyl group (-COOH) becomes smaller. The amount of the component (A) and / or the amount of the cross-linking agent is smaller, and the same degree of cross-link density is obtained. Therefore, it is possible to reduce the polarity of the entire polymer,
This results in a lower Tg, and thus a more viscoelastic and elastic property, which improves the conformability and adhesion to the skin.

(B) Even with the same cross-linking point density, since the main chains are linked by longer cross-linking segments, the flexibility of the cross-linking part is improved than before, and therefore the conformability to the skin and the adhesion are also improved. .

(C) To obtain the same cross-linking density, a smaller amount of carboxyl group (-COOH) and / or a smaller amount of cross-linking agent is required, so that it becomes an inactive adhesive agent correspondingly and the irritation to the skin is further enhanced. descend.

(D) The medicinal component to be blended is a carboxyl group (-COO
H), or a plaster system in which a component that easily reacts with or cross-links with a cross-linking agent and the like coexists,
The degree of alteration and deterioration is reduced accordingly.

(Ii) Other mechanism of action (1) The component (A) in the weight ratio of (A) to (B) is 0.
When it is 5 or less, the substantial effect disappears. Again 2
Being 0 or above means (a) there is no need for it (ie 2
A suitable range is determined for the reason such that a sufficient effect can be obtained at 0 or less) and that only a low molecular weight (b) can be obtained.

(2) Even if the weight ratio of the component (A) to the component (B) is the same, the properties thereof can be changed or modified to a large extent depending on the composition of the component (B). it can. In general, the tackiness increases as the Tg of the polymer decreases, so that a component that provides a Tg value suitable for the purpose can be selected as the component (B), and the selected component (B) (alone or (A) depending on the Tg of the mixture)
The component ratio of the pair (B) and / or the component ratio of the component (A) and the cross-linking agent are basically determined according to the use and purpose.

(3) Method for preparing degree of crosslinking: (a) Ratio of component (A) to component (B) (b) Prepared by the ratio of component (A) and crosslinking agent.

As the amount of the component (A) increases, it goes without saying that the crosslinking increases, but even if the same degree of crosslinking (and thus cohesive strength) appears, the component (A) is used in excess or the crosslinking agent is added in excess. It is best to decide on a case-by-case basis considering the effects of the purpose, performance and coexisting additive / compounding components (including medicinal components), such as whether to use it for the above or in a well-balanced place. desirable.

For example, when a liquid softening agent that increases plasticity or a compounding agent having the same effect as that other than the polymer is added, the cohesive force is reduced by that amount, and therefore the degree of crosslinking is adjusted so as to increase in advance. In addition, for example, when a drug that is weak in acidity is added, the deterioration of the drug can be prevented by setting the crosslinking agent in a large excess.

Possible component examples (i) Examples as component (B) Alkyl groups as acrylic acid ester residues include n-propyl, n-butyl, isobutyl, n-pentyl, n-
Hexyl, n-heptyl, n-octyl, iso-octyl, 2-ethylhexyl, n-nonyl, iso-nonyl,
Decyl, dodecyl and the like can be mentioned. The alkyl group as the ester residue of methacrylic acid ester is n-octyl,
2-ethylhexyl, n-decyl, n-dodecyl and the like can be mentioned.

(Ii) Other than essential components (that is, other than both components (A) and (B))
Copolymerization component: It is also possible to add another type of monomer as a copolymerization component within the range of 40% by weight or less in the whole polymer for the purpose of merely increasing the amount or adding or modifying special properties. . Examples of such monomers include: vinyl acetate, vinyl proonate, vinyl laurate, fatty acid esters of vinyl alcohol such as dialkyl acrylamide, butoxyethyl (meth) acrylate and the like, alkoxyalkyl (meth) acrylates, Examples include diacetone acrylamide and vinylpyrrolidone.

(Iii) Crosslinking agent Depending on the composition and use, it can be used without being necessarily crosslinked, but the crosslinking further improves cohesive strength. Basically, there are 2 functional groups that can react and bond with carboxyl groups.
Any crosslinking agent having the above can be used. Examples of functional groups are:
There are polyvalent metal ion-releasing substances (polyvalent metals and the like), alkylol groups, isocyanate groups, glycidyl groups, amino groups, and the like. Particularly for medical purposes, metal ion cross-linking, which does not cause skin irritation even with unreacted substances, is preferred.

Examples of the metal ion crosslinking agent include Mg ⁺⁺ , Ca ⁺⁺ , Zn ⁺⁺ ,
Organic carboxylates such as Ti ⁺⁺ and Sn ⁺⁺ are preferable, and specifically, calcium octylate, magnesium laurate, calcium laurate, zinc laurate, magnesium naphthenate, zinc naphthenate, resin acid (or rosin acid). Examples include zinc and calcium resinate.

(Iv) Softening Agent The polymer can be finely modified not only as a polymer but also by adding a softening agent (and an additive as described below) and the like as needed. Examples are: dioctyl phthalate, dibutyl phthalate, dibutyl sebacate, dioctyl adipate, tributyl phosphate, isopropyl myristate, triethyl citrate,
Examples include olive oil and liquid paraffin. In addition, liquid (low molecular weight) polymers of (meth) acrylic acid ester and the like are also possible.

(V) Other additives Inorganic or organic fillers that are insoluble in the system, chemicals, surface active agents, other chemical wetting / migration / absorption aids, colorants, stabilizers, fragrances, etc. Is used as appropriate.

Possible Polymerization Method Generally, the polymerization method used when polymerizing an acrylic pressure-sensitive adhesive is used as it is.

Radical polymerization is the most suitable chemical method.

As the form, any method such as solution polymerization method, bulk polymerization method, emulsion polymerization method, suspension polymerization method may be adopted, but the accuracy, controllability, economic efficiency of the polymerization reaction, quality of the product, after polymerization, The solution polymerization method is most suitable for application of the present invention from the viewpoints of ease of transfer of the subsequent steps, and the like.

Purpose and application Basically, it is intended for medical applications. Therefore, as far as the field of use is concerned, it does not relate to a lower, individual purpose, but as an adhesive for an adhesive member to be attached to the skin, or for an adhesive or an adhesive plaster, etc. It can be widely used as an adhesive base.

A specific product group is one in which a pressure-sensitive adhesive layer containing the above-mentioned pressure-sensitive adhesive as a main component is provided on the surface of a flexible backing support, for example: adhesive plaster (in this case and in the following cases, backing No particular suitability or unsuitability is selected for the support material) and similar adhesive dressings, adhesive drapes in the form of wide sheets, adhesive plasters for extinction and analgesia such as mint rubber plaster, There are various types of medicinal patches containing various medicinal ingredients.

(Example) Below, this invention is demonstrated based on an Example.

Example 1 Polymerization composition 2-acryloyloxyethyl succinic acid (A component) 15 parts by weight Butyl acrylate (B component) 85 parts by weight Ethyl acetate (polymerization solvent) 100 parts by weight A composition having the above ratio was charged into a reaction vessel, and N was added. 60 in ₂ air currents
Polymerization was carried out for a total of 26 hours at 8 ° C. for 8 hours, at 70 ° C. for 8 hours, and at the reflux point (77 to 74 ° C.) indicated by the system for 10 hours. As a polymerization catalyst, 1.2% by weight of the total amount of the above monomers, lauroyl peroxide, was divided into 10 parts in a reaction vessel, and the total amount was dividedly added by 22 hours including the start.

Since the viscosity increases as the polymerization progresses and stirring becomes difficult, the inside of the container was observed and a small amount of ethyl acetate was added if necessary. The additional amount of ethyl acetate was 88 parts by weight. After the polymerization was complete, a very viscous solution was obtained.
The residual monomer concentration in the obtained polymer solution was measured by gas chromatography, and the polymerization rate calculated from it was about 98.7%. The weight average molecular weight as a pure polymer component dried from the obtained solution (which was measured by the CPC method) was about 480,000, and the second-order transition temperature (Tg) of the pure polymer was also measured by the DSC method. It was about -51 ° C. Further, the content weight ratio of the carboxyl group (-COOH) in the polymer is about 3.1%.

Example 2 Polymerization composition 2-acryloyloxyethyl succinic acid (component A) 4 parts by weight Acrylic acid-dodecyl (component B-1) 58 parts by weight Methacryl n-butyl (component B-2) 38 parts by weight Ethyl acetate (solvent) 60 parts by weight The composition of the above proportion was charged into a reaction vessel, and polymerization was carried out by the same polymerization method and conditions as in Example 1. By the end, 20 parts by weight of solvent was further added to obtain a viscous polymer solution. The polymerization rate of the polymer was about 99.6%, the weight average molecular weight of the polymer was about 640,000, and the second-order transition temperature (Tg) of the polymer was about -38 ° C by the DSC method. The weight ratio of the carboxyl groups contained in the polymer is about 0.8%.

Example 3 Polymerization composition 2-acryloyloxyethyl succinic acid (component A) 10 parts by weight Acrylic acid-octyl (component B) 65 parts by weight Vinylpyrrolidone (other components) 25 parts by weight Ethyl acetate (solvent) 70 parts by weight The above ratio The composition was charged in a reaction vessel and polymerized by the same polymerization method and conditions as in Example 1. By the end, 30 parts by weight of a solvent was added to obtain a viscous polymer solution. The polymerization rate of the polymer is about 99.3%, the weight average molecular weight of the polymer is about
590,000, the second-order transition temperature (Tg) of the polymer was about -43 ° C by the DSC method. The weight ratio of the carboxyl groups contained in the polymer is about 2.1%.

The polymers obtained in Examples 1 to 3 have a minimum cohesive force that can be used as a practical pressure-sensitive adhesive as it is, unless a softening agent is added to the polymer. Cannot be made too thick (eg, 30 μm or more). To add a softening agent, an absorption aid, and the like, and to obtain a well-balanced pressure-sensitive adhesive or pressure-sensitive adhesive plaster, for example, a metal ion cross-linking agent or the like is added so that at least a part of the contained carboxyl groups is cross-linked. It is desirable to have a measured composition.

Comparative Example 1 Polymerization composition Butyl acrylate 98.7 parts by weight Acrylic acid 1.3 parts by weight Ethyl acetate (solvent) 100.0 parts by weight The composition having the above ratio was charged in a reaction vessel and polymerized by the same polymerization method and conditions as in Example 1 to obtain a viscous resin. A viscous polymer solution was obtained. The polymerization rate of the polymer was about 98.1%, the weight average molecular weight of the polymer was about 290,000, and the second-order transition temperature (Tg) of the polymer was about -52 ° C by the DSC method. The weight ratio of the carboxyl groups contained in the polymer is about 0.8%.

Comparative Example 2 Polymerization composition 2-Ethylhexyl acrylate 95.0 parts by weight Acrylic acid 5.0 parts by weight Ethyl acetate (solvent) 100.0 parts by weight A composition having the above ratio was charged in a reaction vessel and polymerized by the same polymerization method and conditions as in Example 1 to obtain a viscous resin. A viscous polymer solution was obtained. The polymerization rate of the polymer is about 98.4%, the weight average molecular weight of the polymer is about 320,000, and the second-order transition temperature (Tg) of the polymer
Was about -48 ° C by DSC method. The weight ratio of the carboxyl groups contained in the polymer is about 3.1%.

<Comparative Test> Comparative Test-1 A comparison was made in the case where the polymers obtained in Examples and Comparative Examples were used as they were as an adhesive without adding an additive such as a crosslinking agent.

One side of a 35 μm thick polyether polyurethane film (having an elongation of 300% or more at break)
Each of the polymer pressure-sensitive adhesive solutions of Examples 1 to 3 and Comparative Examples 1 and 2 was applied by a transfer coating method so that the thickness after drying was within the range of 15 ± 3 μm, and the adhesive layer surface had releasability. Each comparative sample was made in the form of an adhesive drape with the protective paper eventually applied.

A test piece for sticking of 5 cm × 5 cm was prepared from each sample, and stuck on the upper arm of the human body, peeled after 1 day, and whether or not there is peeling up to that point and practical adhesiveness depending on the feeling at the time of peeling, The cohesive strength of the pressure-sensitive adhesive and the like were determined depending on how the pressure-sensitive adhesive spreads to the periphery and the presence or absence of the cohesive failure phenomenon of the pressure-sensitive adhesive layer when peeled off.

The results are as follows, and the comparative examples (2 examples) were all satisfactory in terms of tackiness, but clearly showed that they did not reach the practical level in terms of cohesive strength. It was In all of the three examples, the practical level was reached.

Results of Examples Adhesiveness: In Examples 1, 2 and 3, neither peeling nor any sign of peeling was observed during the period from the initial application to the end (after 1 day).

When it was peeled off, no pain was given, but it gave a feeling of pulling the skin surely and showed a sufficiently high adhesive strength (equivalent to 200 to 250 g / cm in terms of numerical value).

Cohesive strength: In Examples 1, 2 and 3, the pressure-sensitive adhesive squeeze-out to the periphery at the end of application was within the range of 0 to 2 mm.

A local stringing phenomenon was seen in the state of peeling,
The stringed part finally peels off at the interface with the skin surface and restores viscoelasticity toward the original adhesive sheet side, and almost no adhesive residue is observed on the skin surface after peeling. None (whitening or no color in the chalk test).

From this, all of Examples 1, 2, and 3 had practicality for drape.

Results of Comparative Example Adhesiveness: In Comparative Examples 1 and 2, no peeling phenomenon was observed until the end of application.

The tackiness when peeled off was weaker than that of Examples 1 to 3 (corresponding to 150 to 200 g / cm in terms of numerical value).

Cohesive strength: In Comparative Example 1, the protrusion of the adhesive to the periphery at the end of application is 2 to 5 mm, and in Comparative Example 2, it is 1 to 4 mm,
It was shown to have fluidity as compared with the examples.

During the peeling process, the adhesive caused a small stringing phenomenon, which was mostly left on the skin due to the cohesive failure phenomenon. This phenomenon was observed in both Comparative Examples 1 and 2, but when the two were compared, Comparative Example 1> 2, which was relatively clear even in the chalk coloring test.

Comparative test-2 Assuming the same conditions as the patch preparation containing the medicinal components, the composition of the cross-linking agent and the skin absorption aid, etc., which are considered to be suitable, and the amount of the same cross-linking agent for some comparisons are as follows. 110 μm thick soft polyvinyl chloride film (raw resin; Esmedical V / Sekisui Chemical Co., Ltd.)
Then, it was coated by the transfer method so that the thickness after drying would be 80 μm, and this was used as a test sample for a 40 mm × 40 mm square sticking test and for a 15 mm × 100 mm (or more) measurement test. It was prepared separately.

(Crosslinking agent) Magnesium oleate was adopted as a crosslinking agent for metal ion crosslinking, and this was used as a 5% ethyl acetate solution.

(Aid for percutaneous absorption of drug) A 1: 1 weight ratio mixture of olive oil and isopropyl myristate was used.

(Compounding) As shown in Table 1, the individual preferable compositions were A to E, and the compositions for partial comparison were F and G. However, each composition is a ratio by weight per 100 parts by weight of each polymer component.

The 180 ° peeling force, ball tack and holding force of the pressure-sensitive adhesive tape were generally measured for the measurement samples prepared in the form of tape. However, the test method was based on the following.

Adhesion: JIS-Z-1522 "Peeling method adhesion" Tack: JIS-Z-0237 "Rolling ball tack value" Retention: JIS-Z-1528 "Retention test method" Composition and results are shown in Table 1. And shown in Table 2.

Comparative test-3 The simulated patch (4 cm x 4 cm) prepared in Table 2 was applied to the left and right upper chests, and the state after 24 hours (end), the state of the skin after peeling, etc. were observed. The results are shown in Table 3.

(Effect of the Invention) Since the medical adhesive and medical patch of the present invention are configured as described above, they have the following effects.

By using the component (A) even with the same carboxyl group content, the reactivity thereof becomes higher than in the conventional case, so that the crosslinking effect is enhanced and the one having higher cohesive force is obtained.

To obtain the same cohesive strength, the required carboxyl group content or the amount of added cross-linking agent is smaller than before, so there is room to modify the composition and composition in various ways, lower Tg, and adhesiveness. Is provided with an adhesive agent or an adhesive agent having higher elasticity.

Since the flexibility of the cross-linked portion is greatly improved, the same degree of cross-linking (cohesive strength) gives a softer feeling and improves the familiarity of the skin.

By the combination of the above and, the following synergistic effects are further produced.

If the carboxyl group content is the same, the conventional composition (eg:
Since an equivalent cohesive strength is achieved with a smaller amount of cross-linking agent than is required in the case of (acrylic acid) instead of the component (A), the unreacted portion of the component (A) segment is converted into an excess side chain having a carboxyl group. However, since this carboxyl group has flexibility derived from the side chain length thereof, it brings about a very large effect of improving the adhesive force.

On the other hand, in the conventional case, simple (meth) acrylic acid, maleic anhydride, etc. do not give the adhesive strength-enhancing effect as much as the component (A) even if they are left as excess carboxyl groups.

Even in the non-crosslinked system, the composition of the present invention is superior to the prior art. Comparing this with the case of the same carboxyl group content, the present invention provides a flexible adhesive agent in which the mutual effect of the adhesive forces on the carboxyl groups is greater and the Tg is lower at the same time. Therefore, "when the low cohesive strength due to non-crosslinking is supplemented with the A component, it is even more flexible, the Tg is low, and high adhesiveness is exhibited." ) When supplemented with acrylic acid etc., Tg has already reached a point where it has risen considerably, and the adhesive strength improving effect due to its lack of flexibility and its carboxyl group is greater than that of component (A). Low.

It gives an adhesive with less skin irritation. For example, the polymerization rate of the component (A) is higher than that of the component (B) which is copolymerized with (meth) acrylic acid, maleic anhydride, or the like. Even if the amount remains, the component (A) has far less toxicity and irritation.

Since a polymer having a larger molecular weight is provided, medical adhesives and patches having excellent various properties can be obtained.

Claims (2)

[Claims] 1. A copolymer obtained by copolymerizing (A) 2-acryloyloxyethylsuccinic acid and (B) (meth) acrylic acid alkyl ester and having a second-order transition temperature of -15 ° C. to -73 ° C. A medical pressure-sensitive adhesive comprising the copolymer of 2. A medical patch comprising the adhesive layer containing the medical adhesive according to claim 1 as a main component on the surface of a flexible backing support.