Method For Imparting Pressure Sensitive Adhesion To Velvet Type Fasteners

Abstract

Velvet type fasteners are imparted with pressure sensitive adhesion by applying to the respective back surfaces of the male and female pieces of a velvet type fastener, a composition consisting of: 100 parts by weight of a polymer, containing at least 65 percent mol of an ester of an acrylic acid or methacrylic acid and from 0.2 to 5 parts by weight of glycidyl ester of an unsaturated organic acid; from 0.5 to 5 parts by weight of a zirconyl salt of organic acid, and; from 0.01 to 0.1 part by weight of a volatile acid addition salt of organic amine.

Description

The present invention relates to a method for imparting pressure sensitive adhesion to velvet type fasteners. More particularly, it relates to a method for imparting pressure sensitive adhesion to the respective back surfaces of the male and female pieces of velvet type fasteners.

It is well known that there are two different kinds of velvet type fasteners. One of them is a fastener composed of a male piece having a plurality of upright hook elements disposed on a base fabric and a female piece having a plurality of loop elements formed on a working surface of a base fabric. In the other kind of velvet type fastener, a male element is provided with a laterally expanded cap formed at the top end portion of a stem is utilized instead of the hook element. As to the materials for making these kinds of fasteners, synthetic fibers such as polyamides polyesters, polypropylene and polyoxymethylene fibers have been preferably utilized. This is because the synthetic fibers mentioned above have desirable physical properties such as elasticity, rigidity, flexibility, thermal stability and strength. The term "velvet type fastener" or "fastener" used herein refers to the above-mentioned two kinds of fasteners.

It is also known that the velvet type fastener has been widely utilized for clothing, interior decorations and industrial materials, including woven and knitted fabrics of various types, because of the velvet type fastener's easily detachable fastening of a pair of articles.

Generally, the male and female pieces have been secured on woven and knitted fabrics by sewing. However, it has been difficult to carry out such a sewing operation owing to the presence of the engaging elements of the male and female pieces and, in addition, the engaging elements of these pieces have many times been partly sewn in by the sewing thread. The inevitable consequences of these problems have been lower securing efficiency and poorer fastening effect. For thick or stiff materials such as carpet, natural or synthetic wood and shaped resinous articles, it has been very difficult or impossible to effect the above-mentioned sewing operation.

To overcome the above problems, it has been proposed to impart heat sensitive adhesion or pressure sensitive adhesion to the back surface of each piece of the fastener. In the former method, the heat sensitive adhesion is imparted by coating a heat meltable resin layer onto the respective back surfaces of the male and female pieces. However, it is necessary that each piece of the fastener obtained by this method be secured by being pressed under an elevated temperature satisfactory to melt the resin. This often results in damage to the pieces from both or either the pressure and/or the heat applied. On the other hand, the fastener obtained with pressure sensitive adhesive agents according to the latter method is not subject to the above-mentioned drawbacks and each piece is easily secured to the desired materials. However, in the case where the fastener is composed of synthetic fibers, the conventional pressure sensitive adhesive agents tend to loose their adhesion to the back surfaces of the pieces of the fastener during repeated fastening. In addition, shear between the fastener and the material secured to the fastener often occurs owing to creep of the adhesive agent when the fastener and the material are subjected to even a weak shearing force for a long period of time.

The principal object of the present invention is to provide a method for imparting pressure sensitive adhesion which enables a velvet type fastener to be secured easily and quickly to the material on which the fastener is used said fastener and possessing excellent adhesive strength and creep resistance in practical use.

The object of the present invention can be accomplished by applying an adhesive composition of the nature disclosed hereinafter to the velvet type fastener.

The method according to the present invention is a novel method for imparting pressure sensitive adhesion to velvet type fasteners, comprising applying to the respective back surfaces of the male and female pieces of a velvet type fastener composed of synthetic fibers, a composition consisting of: 100 parts by weight of a polymer, containing at least 65 percent mol of an ester of acrylic acid or methacrylic acid and from 0.2 to 5 parts by weight of a glycidyl ester of an unsaturated organic acid; from 0.5 to 5 parts by weight of a zirconyl salt of organic acid, and; from 0.01 to 0.1 part by weight of a volatile acid addition salt of an organic amine.

It has been found that the method of the present invention can suitably impart superior and stable adhesive strength and creep resistance to the velvet type fastener. The velvet type fastener to which the adhesive composition according to the present invention has been applied can be secured easily and quickly to the desired materials.

The velvet type fasteners composed of synthetic fibers and usable for the method of the present invention include fasteners composed of the fibers such as polyamides, polyesters and polyolefins. For example, woven or knitted multifilament yarn fabrics of polyamides or polyesters may be suitably used for the loop elements and the base fabric of the female piece, and woven or knitted fabrics of densified polyethylene, polypropylene or polyvinyl chloride as well as fabrics of polyamides or polyesters may be suitably used for the base fabric of the male piece, because of their desirable properties such as tensile strength and elasticity. For the male elements which may be in hook form or in the laterally expanded cap form at the top end portion of the stem, a monofilament yarn of polyamides, polypropylene polyethylene, polyoxymethylene or the like may be suitably used in view of the necessity of excellent elasticity and rigidity. Of the above, the polyamides are preferably utilized for the loop elements of the female piece and the base fabrics of the male and female pieces and also polypropylene is preferably utilized for the engaging male elements of the male piece.

The ester of the acrylic acid or methacrylic acid usable for the adhesive composition according to the present invention includes acrylic and methacrylic esters having at least two carbon atoms in the alkyl moiety, such as ethyl acrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate. Preferably, butyl acrylate and 2-ethylhexyl acrylate are used. For the polymer containing at least 65 percent mol of acrylic or methacrylic ester, copolymers of an acrylic or methacrylic ester with a polymerizable monomer such as vinyl acetate, methyl methacrylate and styrene may be used. The copolymers may optionally comprise unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid. The acrylic or methacrylic ester mainly participate in the pressure sensitive adhesion. When the ester is present in an amount of less than 65 percent mol in the polymer, the pressure sensitive adhesion of the fastener with the adhesive composition applied is undesirably reduced. The monomers copolymerized with the above ester participate in yielding "hard" polymers. The monomers serve to control the tacking, improve the cohesive adhesion and also to elevate the creep resistance, of the adhesive composition.

The glycidyl ester of unsaturated organic acid which is a component of and usable for the polymer in the pressure sensitive adhesive composition may be the glycidyl esters of acids such as acrylic acid, methacrylic acid and crotonic acid. These glycidyl esters impart creep resistance and thermal stability to the adhesive composition and are suitably used in an amount of from 0.2 to 5 parts based on the weight of 100 parts of the polymer. The glycidyl esters also react with a zirconyl compound as described hereinafter. When the glycidyl esters are used in an amount of less than 0.2 parts, it is difficult to obtain appropriate cohesive adhesion and creep resistance, while when the glycidyl esters are used in an amount of more than 5 parts, the stability of the composition and the durability of the pressure sensitivity are reduced, more or less depending on the amount of the added zirconyl compound.

It should be noted that the most important features of the method of the present invention are that a specific amount of the zirconyl salt of an organic acid is added in the composition, and that the volatile acid addition salt of the organic amine is also used as an accelerator for the reaction of the zirconyl compound with the polymer. The resinous composition comprising the polymer containing mainly the acrylic or methacrylic ester and partly the glycidyl ester of unsaturated organic acid, but not comprising the above-mentioned zirconyl compound and amine compound, is known as a reactive acrylic resin. These known types of resinous compositions are generally utilized in the flocking of textile articles. However, these known compositions cannot be utilized for the purpose of the present invention, because they are inferior in adhesion to the fastener, in durability of the adhesion and also in creep resistance. In addition, it is necessary that these compositions be cured at a high temperature for a long period of time, after coating, for the prevention of the gelation of the composition owing to the change of viscosity during practical use thereof.

The zirconyl salts of the organic acid usable for the present invention include, for example, zirconyl acetate, zirconyl propionate, zirconyl caprate and zirconyl stearate. Particularly, zirconyl salts of higher fatty acids are preferably used. The suitable amount of the zirconyl salts is from 0.5 to 5 parts based on the weight of 100 parts of the polymer, while they are preferably used in a range between 70 and 120 percent, based on the weight of the glycidyl ester of unsaturated organic acid. In the case where the zirconyl compounds are used in an amount of less than 0.5 part based on the weight of 100 parts of the polymer, or less than 70 percent based on the weight of the glycidyl ester, appropriate adhesion and durability of adhesion of the resultant composition cannot be obtained. On the other hand, when the zirconyl compounds are used in an amount of more than 5 parts, based on the weight of 100 parts of the polymer, durability of pressure sensitivity of the composition becomes inferior and the obtained fastener feels unpreferably hard. The use of the zirconyl compounds in an amount of more than 120 percent based on the weight of the glycidyl ester does not, to a large extent, increase the effects for adhesion or creep resistance and, therefore, is uneconomical.

It should also be noted that the other important features of the present invention are that the adhesive composition used in the present method is stable under acidic conditions and that the composition is in the acidic pH range owing to the presence of the acid addition salt of the organic amine. The composition is very stable at a pH below 6, preferably at a pH below 5.

The volatile acid addition salts of the organic amines include, for example, the salts of mono-, di- or triethanolamine or mono-, di- or tripropanolamine with acids, readily and relatively volatilized by heat, such as hydrochloric acid and acetic acid. These acid addition salts exhibit acidic properties and can control the cohesive adhesion and the durability of adhesion of the resultant composition as mentioned above. Therefore, the composition containing the acid addition salts is slowly reacted while volatilizing the acid after being coated onto the fastener and produces excellent adhesion and creep resistance. When the composition is heated after being coated, it rapidly volatilizes the acid and also produces the above-mentioned effects. For such effects, the composition according to this invention may optionally comprise a small amount of hydrochloric acid, acetic acid or the like. The acid, addition salts of organic amine are suitably used in an amount of from 0.01 to 0.1 part based on the weight of 100 parts of the polymer. When the amount of the acid addition salts is less than 0.01 part, the increasing of the cohesive adhesion of the composition cannot be obtained; while when the amount of the acid addition salts is more than 0.1 part, the pressure sensitivity of the adhesion is lost and the stability during storage becomes slightly inferior.

The adhesive compositions usable for the method of the present invention may be prepared as follows. The polymer is firstly prepared by known emulsion polymerization or solution polymerization procedures. The emulsion polymerization may be effected by reacting the desired monomers as mentioned hereinbefore, at a reflux temperature or in a redox system for from 2 to 10 hours, in the presence of from 0.01 to 1 percent, based on the weight of the monomer, of a watersoluble initiator such as hydrogen peroxide, potassium persulfate and ammonium perborate and from 0.1 to 10 percent, based on the weight of the monomer, of an emulsifying and dispersing agent. The emulsifying and dispersing agent may be, for example, nonionic surface active compounds such as a polyoxyethylene alkyl ether, a polyoxyethylene alkylphenyl ether and polyoxyethylene sorbitan monoalkylate; anionic surface active compounds such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate; cationic surface active compounds such as polyoxyethylene laurylamine and lauryl trimethyl-ammonium chloride, and; water-soluble polymers such as polyvinyl alcohol, hydroxyethyl cellulose and carboxymethyl cellulose. These may be used alone or as a mixture. In the above reaction, the glycidyl ester of unsaturated organic acid should be added toward the end of the reaction.

The solution polymerization may be effected according to conventional methods in a medium such as methanol, ethanol and ethyl acetate in the presence of an initiator such as benzoyl peroxide and azobisisobutyronitrile. In general, the polymer obtained by solution polymerization can give better adhesive strength to the resultant composition than the polymer obtained by emulsion polymerization, and solution polymerization is more capable of controlling the operations of the production than the emulsion polymerization.

To the remaining emulsion or solution, a solution or dispersion of the volatile acid addition salt of organic amine in water, alcohols, ethers, ketones or other hydrocarbons are added and stirred so as to be uniformly mixed. Thus, the desired adhesive composition can be obtained.

The adhesive composition this obtained may then be coated on the respective back surfaces of the male and female pieces of a velvet type fastener by conventional coating methods such as doctor coating, roll coating and spray coating. The suitable amount of the coated composition is in general between 80 and 400 g, preferable 120 and 250 g, based on the dry weight of the composition, per square meter. The coated surfaces of the fastener may then be secured to a releasing paper. Alternatively, the composition may be coated onto a releasing paper and, after semi-drying, the coated surface of the releasing paper is secured to the respective back surfaces of the two pieces of a velvet type fastener. Then, the composition which may be sandwiched between the fastener and the releasing paper is dried at a temperature below 80.degree.C, preferably below 60.degree.C. The fastener thus obtained and the releasing paper may then be rolled up together.

The features of the adhesive composition and the structure of the velvet type fastener according to the present invention are further illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a graph showing ductility (heat flowability) of the composition heat treated at various temperatures plotted against the pH of the original composition prior to the drying and the heat treatment;

FIG. 2 is a partial section view of the male and the female piece of the fastener obtained by the method of the present invention.

Referring to FIG. 1 ductility (heat flowability) of the composition dried at room temperature and heat treated at the indicated temperatures is plotted against the pH of the original composition prior to the drying and the heat treatment. The composition was prepared by adding 2 parts by weight of zirconyl stearate to 250 parts by weight of a 40 percent emulsion of a polymer of 86 parts by weight of acrylic acid butyl ester, 12 parts by weight of styrene and 2 parts by weight of acrylic acid glicidyl ester. To the mixture 0.05 parts by weight of monopropanolamine hydrochloride was added and then hydrochloric acid or ammonia was added. Five kinds of compositions having respective pHs of 3.2, 5.4, 6.2, 7.1 and 8.7 were produced from the obtained composition. Each of the compositions was flowed onto a glass sheet and dried at room temperature and then heat treated at 30.degree., 50.degree., 80.degree., 100.degree. and 150.degree.C, respectively. The heat treatment was effected for 5 seconds and 20 seconds. The species of the compositions thus obtained were then subjected to the following test for ductility. The species of 5 .times. 5 mm were pressed by a load weighing 14 kg/cm.sup.2, at 40.degree.C, and for 1 minute, their ductility by percentage was determined. In FIG. 1, the solid lines show the ductility on the heat treatment for 5 seconds and the dotted lines show the ductility on the heat treatment for 20 seconds.

From FIG. 1, it is evident that the self-cohesion of the composition according to the present invention is intimately connected with the pH and the heat treatment temperature. It is also evident that the heat treatment of the composition can desirably impart excellent cohesive adhesion to the composition by volatilizing the volatile acid from the acid addition salt of organic acid. The suitable heat treatment temperature is from 80.degree. to 160.degree.C, preferably 100.degree. to 130.degree.C and the suitable heat treatment time is from 15 seconds to 3 minutes. Heat treatment at a temperature higher than 160.degree.C risks damaging the fibers of the fastener. The composition, the ductility of which is below 100 percent, gives an undesirable hard feel to the fastener.

Referring to FIG. 2, a velvet type fastener according to the present invention comprises a male piece 1 and a female piece 2. The male piece 1 is composed of a base fabric 3, a plurality of engaging elements 4 projecting perpendicular to the face surface of the base fabric 3, a pressure sensitive adhesive composition layer 5 covering the back surface of the base fabric 3 and a releasing paper 6 secured provisionally to the composition layer 5. Each engaging element is provided with a laterally expanded cap formed at the tip portion. However, in the fastener according to the invention, the engaging element may also be in a hook form. On the other hand, the female piece 2 is composed of a base fabric 7, a plurality of upright loops 8 projecting from the face surface of the base fabric 7, a pressure sensitive adhesive composition 9 covering the back surface of the base fabric 7 and a releasing paper 10 secured provisionally to the composition layer 9.

According to the method of the present invention, excellent pressure sensitive adhesion can be imparted to velvet type fasteners composed of synthetic fibers. The fasteners can be easily and quickly secured by hand pressure to various materials such as textile fabrics, wood, synthetic resin articles, glass and metals. That is, they can be secured even to materials to which velvet type fasteners could not previously be secured by sewing or heat melting. The velvet type fasteners imparted with pressure sensitive adhesion by the method of the present invention possess satisfactorily good strength of adhesion and creep resistance. On repeated usages, the fasteners do not tend to lose their adhesion to the secured materials and, also the adhesive composition does not tend to lose its adhesion to the surfaces of the fastener to which it is applied. The adhesion of the applied composition becomes greater with the aging thereof. The method of the present invention can be effectively applied to the fasteners wherein the base fabric of the male piece is composed of polyamides and the male elements thereof are composed of polypropylene. The male elements composed of polypropylene do not slip out of the base fabric, a common trouble with fasteners to which conventional adhesive compositions are applied. The fasteners obtained by the present method are preferably heated with an iron, hot air or the like which imparts more effective adhesion, creep resistance and wash fastness of the adhesion. The heat treatment is particularly effective in the case where the fasteners are to be exposed to heavy loads or to repeated washings. The fasteners advantageously have desirable softness and flexiblity even after the heat treatment, and these properties are particularly preferable when the fasteners are utilized for clothing.

It is another advantage of the fasteners obtained by the present method that it is not necessary to apply backings to the fasteners. The fasteners possess sufficient adhesion and flexiblity as well as good dimensional stability, and these properties are advantageously improved by the abovementioned heat treatment. Therefore, backings are not needed except in the case where high dimensional stability is desired. Compared with this, backings with thermosetting resins such as aminoplasts or modified thermosetting resins are generally required for the conventional fasteners for the purpose of rendering dimensional stability thereto or fixing the male elements to the base fabric.

As is disclosed hereinbefore, the method of the present invention can advantageously impart excellent pressure sensitive adhesion to the velvet type fasteners composed of synthetic fibers. Further, the fasteners obtained by the method of the present invention can be utilized for clothing such as underwear, as well as for interior decorations and industrial materials, because of their excellent adhesive strength and flexiblity and their easily detachable fastening.

The following examples further illustrate the method and the fasteners according to the present invention, wherein parts are indicated by weight. In the Examples, the creep resistance was determined by securing the adhesive surface of a sample of the fastener having an adherence dimension of 6.25 cm.sup.2 (2.5 .times. 2.5 cm), to a perpendicularly fixed substrate attaching a load of 200 g to the fastening piece and then measuring the shear in mm after 24 hours. The friction strength was determined by tensile test with a Schopper's tensile tester for a sample of the fastener having an adherence dimension of 6.25 cm.sup.2 (2.5 .times. 2.5 cm). The stripping strength was determined at an angle of 180.degree.C by a Schopper's tensile tester for a sample of the fastener of 2 cm width and 10 cm length. Further, the repeated fastening test was carried out, wherein one piece of the fastener was engaged, by pressing with 50 g/cm.sup.2 of pressure, with the other piece, the adhesive surface of which had been secured to a fixed substance and then the former piece was rapidly released from the latter piece. The engaging and detaching was repeated 300 times. In the above test, the adhesive surface of the latter piece had dimensions of 2 cm width and 5 cm length.

EXAMPLE 1

20 Parts of vinyl acetate, 77 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid glycidyl ester, 80 parts of methyl alcohol and 1 part of benzoyl peroxide were added to a three neck glass flask of 2 liters, provided with a stirrer, a reflux condenser and a thermometer, and heated at 60.degree. to 65.degree.C for 8 hours with stirring. As the polymerization proceeded, a translucent viscous polymer solution was obtained. Then, 45 parts of 10 percent solution of zirconyl caprate in a mixture of 50 parts of ethyl acetate with 100 parts of toluole and 0.004 part of monoethanolamine hydrochloride were added to the polymer solution and the resulting mixture was stirred until whole mixture became satisfactorily homogeneous. The obtained composition was of a pH of 5.7, a resin concentration of about 35 percent and a viscosity of 3,000 centi-poises. The composition was then coated over the back surfaces of the male and female pieces of a velvet type fastener by means of a flow coater in such a way that the weight of the component polymer of the coated composition was 160 g per square meter. The solvent was removed by drying in a hot air dryer at 48.degree. to 52.degree.C for 10 minutes and silicone coated releasing papers were attached onto the respective back surfaces of the male and female pieces through the coated resin layers. As to the fastener used herein, the base fabrics of the male and female pieces were composed of Nylon 6 yarn of 210 denier/12 filaments and the engaging elements of the male piece were composed of a polypropylene monofilament yarn of 0.2 millimeter diameter, the top of the element being in a laterally expanded cap form.

The male piece and the female piece of one fastener thus coated were each secured to a plain woven fabric composed of 65 percent polyester and 35 percent cotton by pressing with by hand. The male piece and the female piece of another fastener thus coated were also each secured to a fabric of the same type as the above by pressing by hand and thereafter heating for 15 seconds over the back surface of the secured plain fabric with an iron maintained at 130.degree.C. Then, these specimens were subjected to the tests for strength of adhesion, creep resistance and strength of adhesion on repeated fastening of the male and female pieces. The results are shown in Table I.

For comparison, three other specimens were prepared and tested in a manner similar to that stated above, except that the following respective procedures were employed. Comparison 1: 80 parts of 2-ethylhexyl acrylate and 20 parts of vinyl acetate were used instead of 20 parts of vinyl acetate, 77 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid glycidyl ester. Comparison 2: zirconyl caprate and monoethanolamine hydrochloride were not used. In this case, the composition coated fastener was cured at 150.degree.C for 3 minutes after being secured to the fabric by hand pressure. Comparison 3: monoethanolamine hydrochloride was not used. The results are also shown in Table I.

Table I __________________________________________________________________________ Creep Friction Strip- resist- strength ping Repeated fastening No. ance strength test (mm) (kg/cm) (kg/cm) __________________________________________________________________________ 1. The 0.7 25 3.2 Appearance not changed invention stripping strength: (not heated) 2.9 kg/cm 2. The trace 32 4.9 Appearance not changed invention stripping strength: (heated) 4.5 kg/cm 3. Comparison Fastener released 1 4.6 17 1.2 from the object after about 180 times of repetition 4. Comparison Fastener released 2 6.3 14 0.7 from the object after about 60 times of repetition 5. Comparison Fastener released 3 5.9 13 0.9 from the object after about 80 times of repetition __________________________________________________________________________

From Table I, it is evident that the fastener to which the adhesive composition was applied, according to the present invention, exhibits superior and stable strength of adhesion and creep resistance. Further, the fastener indicated as No. 2 in Table I was subjected to the following washing test. The fastener was washed with water containing 0.2 percent of Monogen (fatty alcohol ester, Daiichi Kogyo Seiyaku Kabushiki Kaisha, Japan) and 0.2 percent of washing soda at 40.degree.C, for 15 minutes, by a conventional washing machine, and dried with air at 30.degree.C for 30 minutes. After five repeated washing tests, the friction strength and the stripping strength were reduced about 10 percent and about 20 percent, respectively. However, the fastener was satisfactory for practical use.

EXAMPLE 2

Adhesive compositions were prepared by the same process as in Example 1 by adding triethanolamine hydrochloride and zirconyl stearate each in amounts as indicated in Table II, to the polymer solution prepared as in Example 1, except that 83 parts of butyl acrylate, 16 parts of styrene and 1 part of acrylic acid glycidyl ester were used instead of 20 parts of vinyl acetate, 77 parts of 2-ethylhexyl acrylate and 3 parts of methacrylic acid glycidyl ester. Each of the adhesive compositions was coated onto the releasing surface of a silicone coated releasing paper by roll coating and the coated paper was dried at 50.degree.C for 6 minutes. Then, the adhesive composition thus coated was secured to the respective back surfaces of the male and female pieces of a velvet type fastener of the same type as in Example 1, together with the releasing paper, and further dried at 40.degree.C for 10 minutes. One piece of the fastener was secured to a plywood consisting of lauan and the other piece of the fastener was secured to a twill woven fabric composed of Nylon 6, by pressing each piece by hand, and these were heated by hot air at 120.degree.C for 15 minutes. The obtained specimens were subjected to the tests as in Example 1. The results are shown in Table II.

Table II __________________________________________________________________________ Creep Friction Composition resistance (mm) strength (kg/cm) Repeated fastening test zirconyl amine plywood fabric plywood fabric compound compound __________________________________________________________________________ Comparison 0.4 0.06 6.2 7.3 14 8 Fastener released from the object after about 140 times of repetition The 0.6 0.06 0.9 1.0 24 22 Appearance not changed invention Comparison 2.0 0 3.2 4.1 12 10 Fastener released from the object after about 30 times of repetition The Appearance not changed invention 2.0 0.02 0.7 0.9 25 21 The 2.0 0.06 trace trace 32 29 Appearance not changed invention The 2.0 0.08 trace trace 34 31 Appearance not changed invention Comparison 2.0 0.12 trace trace 33 30 Appearance not changed (rough and hard feel in hands) The invention 4.0 0.06 0.4 0.6 35 31 Appearance not changed Comparison 6.0 0.06 trace trace 35 32 Appearance not changed (rough and hard feel in hands) __________________________________________________________________________

As is evident from Table II, there are certain ranges for the appropriate amounts of organic amine hydrochlorides and zirconyl salts of organic acids. In addition the use of organic amine hydrochlorides and zirconyl salts of organic acids in large amounts does not result in increasing the effect on the friction strength of adhesion, though the creep resistance generally becomes better. The specimens indicated as Nos. 7, and 9 in Table II felt very hard and, therefore, were unsuitable for practical use.

Claims

What we claim is:

1. A method for imparting pressure sensitive adhesion to velvet type fasteners, comprising applying to the respective back surfaces of the male and female pieces of a velvet type fastener composed of synthetic fibers, a composition consisting of: 100 parts by weight of a polymer, containing at least 65 percent mol of an ester of an acrylic acid or methacrylic acid and from 0.2 to 5 parts by weight of glycidyl ester of an unsaturated organic acid; from 0.5 to 5 parts by weight of a zirconyl salt of organic acid, and; from 0.01 to 0.1 part by weight of a volatile acid addition salt of an organic amine.

2. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the composition is adjusted to a pH below 6, preferably below 5, and optionally by adding an acid selected from hydrochloric acid and acetic acid.

3. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the ester of the acrylic acid or methacrylic acid is a member selected from the group consisting of ethyl acrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate.

4. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the polymer is mainly composed of a copolymer of an ester of acrylic acid or methacrylic acid a monomer selected from the group consisting of vinyl acetate, methyl methacrylate and styrene.

5. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the glycidyl ester of the unsaturated organic acid is a member selected from the group consisting of acrylic acid glycidyl ester, methacrylic acid glycidyl ester, and crotonic acid glycidyl ester.

6. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the zirconyl salt of organic acid is a member selected from the group consisting of zirconyl acetate, zirconyl caprate and zirconyl stearate.

7. A method for imparting pressure sensitive adhesion to velvet type fasteners according to claim 1, wherein the volatile acid addition salt of the organic amine is a salt the group consisting of selected from the salts of mono-, di- or triethanolamine or mono-, di- or tripropanolamine with hydrochloric acid and acetic acid.

8. A velvet type fastener composed of synthetic fibres which has applied to the respective back surfaces of the male and female pieces thereof a composition consisting of: 100 parts by weight of a polymer, containing at least 65 percent mol of an ester of an acrylic acid or methacrylic acid and from 0.2 to 5 parts by weight of a glycidyl ester of an unsaturated organic acid; from 0.5 to 5 parts by weight of a zirconyl salt of an organic acid, and; from 0.01 to 0.1 part by weight of a volatile acid addition salt of an organic amine.