DE2206571A1 - Adhesive mass and process for its production - Google Patents

Description

22Q6571

Croda International Limited, Cowick Hall, Snaith, Goole,

Yorkshire, England

Adhesive mass and process for its production

The invention relates to an adhesive mass and a method for its production »

Aqueous emulsions of polyvinyl acetate are widely used as adhesives. Such emulsions can often already, can be used with minor modifications, if any, although it is usually necessary to either to change the physical properties and / or the application properties. Therefore, various modifiers can be used can be added to change such factors as viscosity. Such polyvinyl acetate emulsions

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Sions reveal their adhesive properties by drying them out of the emulsion or by adding them another polymer have been modified, cure by heat.

The invention relates to an adhesive composition which (a) .an aqueous emulsion of a copolymer of vinyl acetate and a compound of the general formula (I)

₀ = C - C - R - OH 2 ι Ii 2

R. O

wherein R- is hydrogen or a lower alkyl group and Rp mean a divalent bridging group, and (b) a catalyst, the ein.Säure or an acidic reacting covalent compound of a metal of groups IV to VIII of the periodic table is, contains.

Suitable compounds of the general formula (I) are hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. However, the preferred compound of the general formula (I) is N-methylolacrylamide. In this case, R _{1 is} hydrogen and R _{2 is} -MCH ₂ . _x

In addition, a third monomer can be added during formation of the copolymer can be added, whereby a terpolymer is formed. Suitable third monomers include ethylene and any desired acrylate compounds of the general formula

a CH-COOR

wherein R is a hydrocarbon radical. Adhesive mass, those with such terpolymers, e.g. an ethylene / vinyl acetate /

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N-methylolacrylamide terpolymers, are generally more calibrated after hardening than those formed with a simple copolymer.

The aqueous emulsions of the vinyl acetate copolymers preferably contain the usual additives, such as polyvinyl alcohol, an emulsifier such as a sulfonated ethyl-oleyl alcohol, Buffers, catalyst initiators, defoamers, preservatives and polymerization catalysts.

If the catalyst is an acid, then it can e.g. molybdic acid, o-phosphoric acid, hydrochloric acid, hydrobromic acid, Hydriodic acid, sulfuric acid, sulfamic acid or toluene-p-sulfonic acid. If the catalyst has a is covalent metal compound of a metal of groups IV to VIII of the periodic table, then this can, for example a titanium halide, such as titanium (IV) chloride or titanium (II) chloride, Zirconium oxychloride, zirconium sulfate, a tin halide, such as tin (IV) chloride, vanadium pentoxide or iron (III) chloride be.

Preferably the catalyst is a covalent compound of a metal from group IV of the periodic table

The catalyst can also be used in conjunction with a material that exhibits the effectiveness of radio frequency (RF) heating of the mixture increases. Such a material is in particular sodium chloride and kaolin or china clay.

The proportion of the compound of the general formula (I) can be 0.5 to 15% by weight, based on the weight of the vinyl acetate. Amounts greater than 15% are suitable, but not economically. The preferred amounts are 1 to 6% by weight, with amounts of 2 to 2% by weight being more preferred.

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The catalyst is preferably added in the form of an aqueous solution. For example, Zinh (IV) chloride is preferred added as a 50% (weight) solution of SnCl «^ ELO in water. The amount of catalyst can vary widely, but is preferably between 1 and 10% of the above solution, based on the volume of the vinyl acetate copolymer emulsion used.

If sodium chloride is used then it is preferably the emulsion in the form of a saturated aqueous solution in an amount of between 1 and 10% by volume, based on the volume of the emulsion, added. The sodium chloride can, if desired, be dissolved in the catalyst solution.

When kaolin is used, it is preferably present in an amount of from 8 to 1 + 0 percent by weight based on the weight of the vinyl acetate polymer. The use of about 32% by weight kaolin is particularly preferred.

Another object of the invention is a method for producing an adhesive composition, which is characterized in that is that an aqueous emulsion of a copolymer of vinyl acetate and a compound defined above of the general Formula (I) forms and that this adds a catalyst which is an acid or a covalent compound Metal of groups IV to VIII of the periodic table to catalyze the thermosetting.

The adhesive of the invention is thermosetting, that is, it solidifies or hardens upon heating or aging. By it cannot be significantly softened again after further heating. The adhesive according to the invention can stored for varying periods of time after addition of the catalyst before its effect becomes irreversible.

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Thus, ζ, B, the adhesive according to the invention, the such catalysts, such as titanium (IV) * chloride, titanium (II) chloride, zirconium sulfate and zirconium oxychloride, can be stored for up to 28 days, with the adhesive at the end of such Can still be used. This behavior is in advantageous contrast to a known one Adhesive mass of a similar type that becomes unusable after a few hours.

In use, the adhesives of the invention are normally cured by heating. The adhesives according to the invention are particularly suitable for applications in which a high-frequency epheating takes place.

The adhesives of the invention cure within a very short period of time when subjected to high frequency heating get abandoned. This behavior makes them special for such areas of application as cable manufacture well suited where the furniture parts assembled using the adhesive over a short period of time be exposed to radiation after which the connections are sufficiently strong that the Handling of furniture items is permitted.

Further uses for the adhesives according to the invention are bookbinding and the production of laminates non-woven fabrics

These two uses are particularly appropriate when the adhesive is made with a terpolymer rather than a simple one Copolymers is formulated because in this case a softer and more flexible cured product is obtained.

Finally, the invention provides a method for forming a connection between two parts of an object

Available, which is characterized in that a mass, as described above, produces the mass towards the Applies connecting parts and subjects the connection to HF irradiation.

As already stated above, make the encore of sodium chloride or of kaolin, the composition of the invention is more sensitive to HF heating, so that better adhesion is obtained when one or more of these two materials are present.

Compared to known adhesives which do not contain any comonomer of the formula (I), the adhesives according to the invention have improved water resistance, It was found that when using N-methylolacrylamide as a compound of the general formula (I), optimum water resistance is obtained when the amount of N-methylolacrylamide is about / f up to 8% by weight, based on the total weight of the adhesive mass, amounts to.

The invention is illustrated in the examples, Example 1

It became an emulsion of polyvinyl acetate and N-methylol acrylamide produced, which had the following composition:

Components% by weight

Vinyl acetate

N-methylol acrylamide 2

Polyvinyl alcohol k

Emulsifier 1.5

The emulsion also contained small amounts of buffers, preservatives, defoamers, a potassium persulfate catalyst to promote the formation of a randomly distributed copolymer of vinyl acetate and N-methylolacrylamide, and a catalyst initiator. The rest (about W?%) Consisted of water

The tin (IV) chloride catalyst solution was prepared by dissolving 50% by weight SnCl, · 5Η ₂ O in water. For the sake of simplicity, the aforementioned polyvinyl acetate emulsion shall hereinafter be referred to as "the emulsion" and the catalyst solution described above shall hereinafter be referred to as "tin (IV) chloride catalyst".

To investigate the adhesives according to the invention, 25 g of the vinyl acetate emulsion with 2 ml of the tin (IV) chloride catalyst and 1 ml of water mixed. This mass was thickened with 8 g of BN / LA grade kaolin. The kaolin used had the following characteristics:

Degree shine
violet shine
yellow Particle size (? <2 , 6
, 0 0.053 mm ph BN / LA
D. 83.7
83.4 4.6
4.6 45 10
¥ f 7 0
1 0.02
0.02 4.5
4.8

The above-mentioned D-degree can also be used, a whiter product is obtained, but the adhesive properties are slightly worse than when used of the BN / LA degree.

The adhesive mass produced in this way was applied to only one surface of one of a pair of wooden strips (BS 120if). The strips were made with a lap joint clamped together by 2.5 * f cm. The bracket.

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pressure was 7 »03 kg / cm. The ones clamped together in this way Strips were irradiated for 20 seconds at a high frequency of 10.7 MHz (at least 1 KV). The clip was then removed. After a further 30 seconds, the Connection pulled apart as laid down in the British standard mentioned above. The breaking load for the four samples treated in this way is given below:

113 kg)

127 kg j

113 kg) breakage of the connections

113 kg j

Example 2

Three further strips, which had been produced according to Example 1, were left to stand for Zk hours before the examination.Then the following results were obtained:

272 kg) * "

JfO8 kg \ breakage of the wood

299 kg)

Example 3

An adhesive was prepared according to Example 1, with the tin (IV) chloride being replaced by a solution of aluminum chloride became. The following breaking loads were obtained during the investigation:

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22Q6571

5kfk kg).

63.5 kg ]

65.8 kg) breakage of the connections

81.6 kg ^

example k

The procedure of Example 3 was repeated, but using wooden strips that were in a chamber with stored for several days at a relative humidity of 90% had been. The following breaking loads were obtained:

27.2 kg)

36.3 kg \ breakage of the connections 31.8 kg)

Example 5

The procedure of Example 11 was repeated, the tin (IV) chloride catalyst being used instead of the aluminum chloride. In this case, the following breaking stresses were found:

81 6th kg 77 1 kg 72, 6th kg Example 6

The procedure of Example 1 was repeated, but the adhesive was produced without kaolin. In this In the 2nd case, the following breaking stresses were obtained:

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- Iu -

81.6 kg 81.6 kg 72.6 kg

Example 7 (comparative example)

The procedure of Example 1 was repeated, except that Tin (IV) chloride has been replaced by aluminum chloride. Included the following results were obtained:

Breaking stresses: Ί-5Λ kg 5 ^ ₉ k kg 5hik kg

In this case it was found that additional amounts of the aluminum chloride catalyst the results did not improve.

Example 8

Several samples which had been produced according to Example 1 were ^{stored for 7 days in water at 20 °} C. and then examined. All samples showed fractures of the wood instead of the joints at breaking loads of more than 272 kg.

It was also found that very good results were obtained when English China Clay Ltd. Grade "A" kaolon was used. A suitable mixture has the following composition:

The emulsion (Example 1) 69 Λ Kaolin grade "A" 18th water 11 , 5 SnCl, · 5H ₂ O 1

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The water / SnCl, »5ELO was used as a separate catalyst solution fed and mixed with the emulsion / clay mixture before use. The resulting mixture is over 24 hours stable"

"Grade A" kaolin has the following properties:

Degree of gloss particle size %

violet <Zii <10u 0.053 mm pH

A 87.5 45 12 0.02 4.5 to His analysis is as follows:

SiO ₂ TiO ₂ ) 47.8 Al ₂ O ₃ 37.3 Fe ₂ O ₃ 0.53 Ti (as 0.04 CaO 21st 0.2 MgO 0.1 K ₂ O 1.72 Examples 9 to

Example 1 was repeated using different catalysts. In Table I, the catalysts used are their concentration and the mean breaking load of at least six trains with a number of different ones © given above.

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Table I.

Example no.

catalyst

Concentration breaking load tion weight% kg

9 10 11 12 13

15th

16 17 18 19 20 Z \

o-phosphoric acid hydrochloric acid

Hydrobromic acid sulfuric acid

6.0

1,

118

168

Hydriodic acid 2.2 156 Toluene-4-sulfonic acid 5.4 122 Sulfamic acid 2.0 (salt 116 solution TitanUD chloride 1.1 191 Tin (IV) chloride 0.8 181 Ferric chloride 6.0 81.6 Zirconium oxychloride 7.0 136 Titanium chloride 2.25 161 Zirconium sulfate 1.44 132

Examples 22 to

Example 1 was repeated using different catalysts were used. The adhesive mass was 7 to 28 days before stored for use. The results obtained are summarized in Table II:

Table II

Example no.

catalyst

Concentration weight

Breaking load kg

22 titanium chloride

2.3 zirconium sulfate

Zk titanium (II) chloride

25 zirconium oxychloride

0.53
0.20
0.50

154 168 102 132

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Claims (1)

22Q6571 Claims U adhesive mass in the form of an aqueous emulsion, thereby marked that they (a) an aqueous emulsion of a copolymer of vinylace tat and a compound of the general formula (I) CH- = C-C-R ₀ -OH ² I Il ² wherein R- is hydrogen or a lower alkyl group and Rp is a divalent bridging group, and (b) a catalyst selected from the group consisting of acids and acidic covalent compounds Metal of groups IV to VIII of the periodic table, contains. 2, mass according to claim 1, characterized net that the compound of the general formula (I) from from the group of hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and N-methylolacrylamide is selected 3 mass according to claim 1 or 2, characterized in that the catalyst selected from the group molybdic acid, Phosphoric acids, hydrochloric acid, hydrobromic acid, hydriodic acid, sulfuric acid, sulphamic acid and toluene-sulphonic acid is selected « / f. Composition according to claim 1 or 2, characterized in that the catalyst is a covalent compound 209835/1183 formation of a metal of groups IV to VIII of the periodic table, selected from the group titanium (IV) chloride, titanium (II) chloride, Zirconium oxychloride, zirconium sulfate, vanadium pentoxide and ferric chloride, 5. Composition according to one of claims 1 to l + _f, characterized in that the catalyst is present as a mixture with sodium chloride or kaolin in order to make the composition more sensitive to HF heating. 6. Composition according to one of claims 1 to 5> characterized in that the connection of the general Formula (I) in an amount of 1 to 60% by weight, preferably 2 to 4 wt% is used. 7. Composition according to claim 5 or 6, characterized in that the kaolin in an amount of 8 to IfO wt .-%, preferably from about 32 wt .-%, based on the Weight of vinyl acetate polymer, is added. 8. Composition according to one of Claims 1 to 7 »characterized in that a third monomer is used to form the copolymer in order to form a terpolymer. , _{; χ} 9, mass according to claim 8, characterized in that that the terpolymer is an ethylene / vinyl acetate / N-methylolacrylamide terpolymer is. 10. A method for forming a connection between two parts of an object, characterized in that a mass according to one of claims 1 to 9 is applied to the parts to be connected and the connection is subjected to HF irradiation. 209835/1183 11. Process for making laminates from nonwoven Flat structures, characterized in that that an adhesive according to one of claims 1 to 9 is applied to the laminate and that the adhesive is applied hardened by HF heating 209835/1183