DK148746B - CLAUSE COLLECTED COLLECTION STREAM AND FOUNDATION TO MAKE A CLAUSE COLLECTED COLLECTION - Google Patents

Description

148746 in o

The present invention relates to an adhesive-assembled can body capable of withstanding retort sterilization so that the portion of the can body adhered with an adhesive does not undergo deterioration even under such conditions where the adhesive-assembled portion contacts hot water. or water vapor at temperatures of 125 ° C or more, as well as a primer for making such an adhesive-packed can body.

10 In the manufacture of cans, so-called tin-free steel plate (TFS) such as chromium-plated steel and chromic acid-treated steel plate with a chromium oxide surface film instead of tinned steel plate have been widely used as metal materials for making cans. Since soldering of these tin-free metal materials is very difficult, the side seam of a can body is made mainly by a method in which the two opposite side edges of a coated metal material to a can body are adhered by an organic adhesive such as a polyamide.

According to this well-known adhesive method, a primer is first applied to both surfaces of a metal material to form the can body, and a polyamide-type molten adhesive is applied between the two opposing edge sides of the metal material, after which the molten material is cooled and solidified during use. pressure to bond the side edges and to form a can body. In accordance with this known method, the side edges of the adhered portion of the can body are adhered to each other by the polyamide adhesive via the primer applied to the surfaces of the metal material.

According to U.S. Patent No. 3,663,354, a primer is used as a primer, a mixture of a phenol resin type resin and an epoxy resin wherein

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The phenol aldehyde resin is prepared from a mixture of phenolic compounds comprising a monovalent phenol, namely β-cresol, and a polyfunctional phenolic compound such as bisphenol A, in a weight ratio of 50-90 / 50-10.

It is not stated in this patent that the adhesive assembly described therein can be subjected to sterilization under strict conditions, namely with water or water vapor, e.g. 125 ° C for 60 minutes and nothing is described about how to form such an adhesive assembly.

According to U.S. Patent No. 3,936,342, as a primer, a material comprising 1 part by weight of thermosetting phenolic resin consisting of a condensation product of a mixed phenol containing 60-10 wt.% O-cresol and 40-90 wt. 15 aldehyde and 0.1-2.5% by weight of a bisphenol A-type epoxy resin having a molecular weight greater than 800. Accordingly, this patent does not use a divalent two-core phenol as the one component of the mixed phenol.

According to U.S. Patent No. 3,993,841, as a primer, a material comprising a phenol formaldehyde resin made by heat condensing phenol with formaldehyde in an amount of less than 1 mole per day is used. moles of phenolic hydroxyl groups as well as an epoxy resin. Thus, according to this patent, a divalent tokenized phenol is not used as the one phenol component. The second phenol, such as bisphenol A, is used in an amount of less than 20% by weight, based on the total amount of phenolic components.

The adhesive assembled portion of a known adhesive assembled can made using the primer known from U.S. Patent No. 3,663,354 has a satisfactory bond strength under normal conditions and has sufficient strength to withstand the pressure of a can content with a spontaneous pressure, e.g. a carbonated beverage. However, the adhesive assembly 3 has

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14-8: 746 part insufficient resistance to hot water. In the case of carbonated beverages, the filling of a can is usually done in a cold state, and since the contents themselves are acidic, no powerful sterilization treatment is needed to preserve the contents.

Therefore, when a carbonated beverage or the like is charged to the can, the hot water resistance of the adhesive assembled part is not particularly important. However, in the case of other foods and drinks, e.g. fruit juice and treating food, in order to preserve its contents, it is necessary to carry out a strong heat sterilization treatment or a scant sterilization treatment or to fill the container in a warm state, and therefore the adhesive compartment part has high resistance to hot water. If the adhesive assembled part has poor resistance to hot water, the can body will easily break during heat sterilization treatment or the airtight property is lost during preservation. This tendency is particularly prominent when there is vacuum or diminished pressure in the interior of the can.

On the other hand, sticky cans have different advantages. For example, the type of metal material to be used is not very critical, and the can manufacture rate, ie. the rate at which the 25 side seams can be formed is very high and the productivity is therefore very high. Therefore, if a can body provided with a side seam formed by an adhesive and with high resistance to hot water can be produced, it will be appreciated that various advantages will be achieved in terms of fabrication costs and resource problems.

It has been found that the resistance to hot water of the adhesive assembled portion of an adhesive assembled can is greatly influenced by the primer to be applied to the metal material and in the adhesive assembled cans made using the U.S. Pat.

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No. 3,663,354 known epoxyphenol resin primers, the adhesive assembled part is not at all resistant to hot water or water vapor heated to 125 ° C.

The higher the temperature that the adhesive compartment of an adhesive compartment can withstand, the more benefits can be gained in preserving the taste and smell of the can. It is known that the time required to destroy bacterial spores can usually be shortened with increasing sterilization temperatures, and it is also known that the taste or aroma and structure or consistency of the food content of the can and dyes and vitamins contained in the food content of the can is degraded and destroyed largely in proportion to the time of sterilization. If the adhesive portion of the can withstand a higher temperature of hot water or steam, the sterilization treatment can be carried out at a higher temperature and terminated over a shorter period of time and it is possible to preserve the can content for a longer period of time without degradation. And destroying the taste or aroma and structure or texture of the product in the can and of the dyes and vitamins contained in the product in the can.

It is therefore the object of the present invention to provide a new retort sterilization resistant primer which is applied to the surface of a metal material prior to adhesive assembly of the metal material to form a can body. It is also the object to provide an adhesive canned body, wherein the portion of the adhesive assembled by means of an adhesive is retort sterilization resistant while at the same time decreasing the peel strength of the portion adhered with an adhesive when substantially sterilized the contents are filled into the can in hot state and where the decrease of the peel strength in the adhesive assembled portion as a function of time is 5

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U8746 regulated to a very low level, although the can content is preserved for a long period of time, as well as a new primer for use in the manufacture of such an adhesive canned body.

The said objects are fulfilled according to the invention

first, with an adhesive assembled can body that can withstand retort sterilization, consisting of a metal plate having the two opposite side edges adhered to a linear polyamide adhesive through an epoxyphenol resin primer containing 50-95% by weight of an epoxy resin of a number of average-diameter sols 800-5500, which is made by condensing an epihalohydrin with bisphenol A, and 5-50% by weight of a phenol aldehyde resin type resin, which adhesive-collected can body is characterized in that the phenol aldehyde resin of the resol type has a number average 200 molecular weight 1000 and is prepared by reaction of a mixed phenol containing 65-98% by weight of a divalent phenol of the general formula I

Wherein R is a group of the formula -CR R - wherein R 2 and R are hydrogen or an alkyl group having up to 4 carbon atoms, a group -O- or a direct bond and 2-35% by weight of a monovalent phenol selected from unsubstituted phenol or phenol substituted with 1 or 30 alkyl groups with up to 6 carbon atoms or with a phenyl group, with formaldehyde in the presence of a basic catalyst.

Second, the objects of the invention are met with a priming agent for the preparation of an adhesive-assembled can body capable of withstanding retort sterilization containing 50-95% by weight of an epoxy resin.

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A resin having a number average molecular weight of 800-5500, prepared by condensing an epihalohydrin with bisphenol A, and 5-50% by weight of a phenolaldehyde resin type resin, which primer is characterized by the phenolaldehyde resin

of the resol type has a number average molecular weight of 200-1000 and is prepared by reaction of a mixed phenol containing 65-98% by weight divalent phenol of the general formula I

Wherein R is a group of the formula -CR R wherein R 2 and R are hydrogen or an alkyl group having up to 4 carbon atoms, a group -O- or a direct bond, and 2-35% by weight of a monovalent phenol selected from unsubstituted phenol or phenol substituted with 1 or 2 alkyl groups with up to 6 carbon atoms or with a phenyl group, with formaldehyde in the presence of a basic catalyst.

Compared to the primer known from U.S. Pat.

25,666,354, the primer according to the invention exhibits the following particular features: 1) the resolol-type phenol aldehyde resin must have a number average molecular weight of 200-1000, which is not mentioned in the U.S. patent, and 2) the divalent phenol and the monovalent resin. phenol is used in the weight ratio 98-65 / 2-35 (or 98/2 to 65/35), whereas the U.S. patent uses ratios of 50-10 / 50-90 (or 50/50 to 10/90) between polyfunctional phenol and monovalent phenol.

35. By this combination of particular features it is obtained that they formed with the primer according to the invention

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7 148746 adhesive collections as opposed to the adhesive collections of the US patent are resistant to retort sterilization, ie. with contact with water or water vapor at temperatures of 125 ° C or more.

5 The significance of it under par. 1) is shown in Example 5 and the accompanying Table V, and the significance of it in section. 2) listed in Example 2 and the associated Table II.

The invention is explained in more detail with reference to the drawing, which illustrates the construction of the present adhesive assembled can, which consists of a wrapper formed by the adhesive collection of untreated canvas wrapper 1 by a side drop 2. This side drop 2 comprises the side edges of the raw can wrapper which is overlapped and adhered by 15 using a polyamide adhesive 3. The raw can wrapper 1 consists of a metal material 4, e.g. undiluted steel plate (TFS) on whose surface a layer 5 of an epoxyphenol resin primer having a particular composition, which is described in greater detail hereinafter, has been applied prior to adhesion by the polyamide adhesive 3. Both side edges of the raw canvas 1 are bonded through this primer layer 5 using the polyamide adhesive.

The invention is described in more detail below.

In the divalent phenol of the above general formula (I) used for the preparation of the resole-type phenol-aldehyde resin, as mentioned, R means a group of the formula -CR R - wherein Rx and R are hydrogen or an alkyl group of up to 4 carbon atoms, a group -O or a direct bond. As preferred examples of the divalent phenol are 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxyphenyl) -butane (bisphenol B), 1,1-bis (4). -hydroxyphenyl) ethane, bis (4-hydroxyphenyl) methane (bisphenol 35 F), 4-hydroxyphenyl ether and p- (4-hydroxyphenyl) phenol.

Among these, bisphenol A and bisphenol B are particularly preferred.

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In the primer used in the present invention, the phenolaldehyde resin is, as mentioned, prepared using a combination of (a) the divalent phenol of the general formula (I) and (b) the above monovalent phenol in a weight ratio (a) / (b) from 98/2 to 65/35, in particular 95/5 to 75/25. It is evident from the data set out in the following Table II that if the amount of the divalent phenol (a) is outside the aforementioned area, an adhesive collected 10 cans made using such a primer will tend to break at a hot water treatment at a temperature above 125 ° C, the peel strength of the adhesive assembly is drastically diminished by the hot water treatment, and the peel strength of the adhesive assembly after the hot water treatment becomes particularly pronounced as time goes on. In contrast, when a dicyclic divalent phenol of the general formula (I) and a monovalent phenol are used in the above-mentioned conditions for the preparation of the phenolaldehyde resin component of the primer of the invention, the adhesive assembled portion of the finished adhesive assembled can body high hot water resistance, ie. the adhesive-assembled portion of the can can adequately withstand a treatment with hot water at a temperature above 125 ° C, and the reduction of the peel strength as a result of the hot water treatment or as a function of time can be brought down to a very low level.

The phenol aldehyde resin type resin used in the present invention is prepared by reacting a mixed phenol with the above composition with formaldehyde in the presence of a basic catalyst such that the number average molecular weight of the resin produced is 200-1000, especially. 250-800.

9

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In the present invention, it is an essential particular feature that the number average molecular weight of the phenolaldehyde resin formed is not less than 200 or greater than 1000. If the number average molecular weight of the phenolaldehyde resin formed is greater than 1000, peel off between polyamide and light peeling occurs easily. and the bonding between the primer and the metal material is easily impaired under the strict sterilization conditions 10 or during storage, cf. Table V.

The number average molecular weight shall be understood to mean the molecular weight determined by a vapor pressure osmometer.

The molecular weight of a phenol aldehyde resin is strongly influenced by such factors as the type of phenol used, the amount of formaldehyde used, the type of catalyst, the reaction temperature and the reaction time, and it is very difficult to give a comprehensive definition of these conditions for the production of a phenol aldehyde resin. 20 phenolaldehyde resin having the above average number molecular weight. Therefore, in practice, the reaction conditions are selected by experiment from the following general conditions so that the number average molecular weight of the phenolaldehyde resin formed lies in the above range.

Usually, the formaldehyde is used in an amount of at least 1 mole, especially 1.5-3 moles per mole. moles of the mixed phenol. The condensation is carried out in the usual manner in a suitable reaction medium and preferably in an aqueous medium. Any of the basic catalysts used heretofore to produce resole-type resins may be used. Among these catalysts, ammonia as well as hydroxides, oxides and basic salts of alkaline earth metals are preferably used, e.g. magnesium hydroxide, calcium hydroxide, barium hydroxide, calcium oxide, basic magnesium carbonate, basic magnesium chloride and basic magnesium acetate. The basic catalyst is used in the reaction medium in a catalytic amount, especially 0.01-0.5 mole percent, based on the phenol component. The condensation conditions are suitably selected from reaction temperatures of 60 to 130 ° C and heating times of 10 minutes to 40 hours.

The resin formed can be purified in known manner.

The resin produced as a reaction product can e.g. is extracted and isolated from the reaction medium with a ketone, an alcohol or a hydrocarbon or mixtures thereof, whereupon, if necessary, the recovered resin is washed with water to remove unreacted substances, the water is removed from the product by azeotropic distillation or by precipitation, and there a purified phenolic aldehyde resin type is obtained which can be mixed with an epoxy resin.

It is usually preferred that the phenol aldehyde resin type thus prepared be combined with an epoxy resin as it is. However, if desired, it is possible to mix the phenolaldehyde resin with an epoxy resin after it has been modified with at least one known modifier such as fatty acids, polymeric fatty acids, resin acids (natural resins), drying oils and alkyd resins.

In the present invention, the primer is prepared by combining the above-mentioned phenolaldehyde resin type resin with an epoxy resin having a number average molecular weight of 800-5500, in particular 1400-5500 synthesized by condensation of an epi-halohydrin with bisphenol A [2.2- bis (4-hydroxyphenyl) propane]. This epoxy resin used in the present invention may be represented by the general formula CH-CH-CEL-O (-R-O-CH-CHo-O-K R-O-CHO-CH-CHO (III) \ 2 y 2, 2 n 2 K / 2

or OH O.

where R is the condensation residue, of 2,2-bis (4-hydroxy-phenyl) propane, and n is such that the number average molecular weight of the resin is 800-5500.

When the number average molecular weight of the epoxy resin is less than 800, the bond strength between the primer and the metal material is low, as shown in the data set forth in the following Table IV, and the adhesive assembly on the finished adhesive can body is peeled off easily when in contact with the hot water.

When the number average molecular weight of the epoxy resin is greater than 5500, as can also be seen in Table IV, insufficient bond strength cannot be obtained, and when the finished adhesive assembled can body comes into contact with hot water, the peel strength is reduced dramatically and the can easily goes break. As mentioned, the molecular weight of the epoxy resin listed is an average value.

It is therefore possible to combine an epoxy resin with a relatively low degree of polymerization, with a linear high molecular weight epoxy resin such that the average molecular weight is in the above range, and to use the resulting mixture as the epoxy resin.

In order to obtain good adhesion between the primer and the metal material or polyamide adhesive and good hot water resistance of the adhesive-packed can body, it is a prerequisite that the aforementioned bisphenol A type epoxy resin (1) be combined with the above-mentioned phenol aldehyde resin (2) phenol resin a weight ratio (1) / (2) of from 95/5 to 50/50, especially from 90/10 to 60/40 for preparing the primer.

When the amount of the resole-type phenolaldehyde resin is less than 5% by weight, based on the sum of the resins (1) and (2), the cure rate of the primer is low and the cure rate is insufficient, and furthermore the peel strength of the highly adhesive composite produced low, often as low as zero upon contact with hot water, as shown in the i

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The following Table III lists the data. When the amount of the phenolaldehyde resin is greater than 50% by weight, the peel strength of the finished adhesive can body is slightly greater in the above case, but 5 is often reduced in practice shortly after contact with hot water or for some time after contact with hot water.

The aforementioned epoxy resin and the aforementioned phenolaldehyde resin can be used as primer 10. in the mixed state and dissolved in a ketone, an ester, an alcohol, a hydrocarbon solvent or mixtures thereof, but it is usually preferred that the resins be precondensed in the dissolved state at 80-130 ° C for about 10 minutes. 1 to approx. 10 hours, after which the preconditioned solution formed is used as primer.

In the manufacture of an adhesive-assembled can body using the present primer, the undercoating material is first applied to the surface of a metal material to form a can wrapper, and the resulting coating is then heated in an oven. Various metal materials intended for the manufacture of cans, e.g. steel plate (black tin), coated steel plate made by plating the steel plate surface with zinc, tin, chromium or aluminum, and treated steel plate formed by subjecting steel plate or black sheet to a chemical treatment with chromic acid or phosphoric acid or an anodic electrolysis treatment. Further, as a metal material, a composite metal material formed by bonding and laminating a metal foil such as aluminum to an organic substrate such as a foil of a resin, e.g. polyolefin, or cardboard. The specific type of metal material to be used is suitably selected taking into account the intended use of the finished adhesive assembled can body. As metal material-

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It is generally preferred to use chromic acid-treated, anode electrolyzed steel sheet comprising a steel sheet substrate, a metallic chromium layer formed on the substrate, and an aqueous chromium oxide layer formed on the metallic chromium layer. an amount of from 0.1 to 2 mg / m, and the aqueous chromium oxide layer is present in an amount of from 0.05 to 5 mg / m, calculated as metallic chromium.

The thickness of the metal material to be used in the manufacture of the adhesive canned body depends on the volume of the wrapper, the type of contents to contain the can, and other factors, but it is usually preferred that the thickness ranges from 0.1 to 0.3 mm.

The aforementioned metal material is degreased with trichlorethylene or other degreasing solvent as needed, and the present primer is applied in the form of a solution on the surface of the metal material 20 in a manner known per se, e.g. for brush application, spray application, immersion, rolling, electrostatic application and electrophoretic application. The thickness of the primer layer is not particularly critical when the metal surface is uniformly coated with the primer, but usually good results are obtained when the thickness of the primer is 1-15 µ.

The primer metal material is then formed into a cylinder at random, and the two opposite side edges are seamed using a known adhesive, e.g. a polyamide adhesive to form a patchwork seam, a longitudinal seam or a long seam. As the polyamide adhesive, linear homopolyamides, copolyamides and modified polyamides having a viscosity fraction of at least 1.5, especially at least 1.8, as measured in a 1% solution in 98% concentrated sulfuric acid, are used. Polymer blends of two or more of these polyamides

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14 can also be used. Examples of such polyamides include homopolyamides such as polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylenedodecamide, polydodecamethylenedodecamide, poly-6-aminapaproic acid, 5 i.e. combinations of dicarboxylic acids and diamine salts or at least two 6) -aminocarboxylic acids, and the above homopolyamides and copolyamides modified with polymeric fatty acids or the like. For the strength of the adhesive assembled part, it is preferred that the polyamide adhesive used is crystalline.

The polyamide adhesive can be applied in different ways between the two edge sides of the coated metal material to be bonded. For example, a preformed strip of a polyamide adhesive may be applied to the two side edges to be bonded, or a molten polyamide in a strip-like form to be melt extruded and applied to the side edges to be bonded. Optionally, polyamide adhesives may also be applied in the form of a powder or solution on the side edges of the metal material to be bonded. The thickness of the layer of the polyamide adhesive applied to the side edges to be bonded is not particularly critical, provided that the polyamide adhesive has uniform and intimate contact with the underlying layer formed on the metal material. However, it is generally preferred that the thickness of the polyamide adhesive layer is in the range of 0.01 to 0.2 mm. The polyamide adhesive may be applied to one or both side edges of the coated metal material prior to the bonding operation, or it may be placed between the two side edges of the bonding operation.

The bonding of the two side edges of the metal material is accomplished by melting the polyamide adhesive disposed between the two opposite side edges of the metal material.

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The material, which is provided with a cylindrical shape, compresses the two side edges of the coated metal material during cooling and solidifies the polyamide adhesive.

A can body made by gluing a side seam in this way is then subjected to known can fabrication processes such as deburring, bertling and lid folding, and thus a finished can is obtained.

When the present primer is used in the manufacture of adhesive assembled cans, a close bonding of the side edges of the metal material with the adhesive is achieved through this primer layer, and an adhesive assembled portion is formed with a good peel strength. Furthermore, this adhesive-assembled portion can effectively withstand severe sterilization treatments with hot water 15 or water vapor at temperatures of 125 ° C for 60 minutes, as shown by the following examples. Furthermore, even when the finished adhesive-assembled can, which has been subjected to such rigorous sterilization treatments, is subjected to long-term storage, the reduction of the peel strength as a function of time can be controlled to an extremely low level.

In retort sterilization of food or beverages in adhesive cans, the condition of the adhesive collection is greatly influenced by the storage temperature.

For example, when foods or beverages placed in cans are stored at relatively low temperatures, e.g. 20 ° C or below, the degradation of the adhesive assembly over time is not so conspicuous, but when the storage temperature is relatively high, e.g. 35 ° C or above, 30 the decay of the adhesive assembly becomes conspicuous over time. However, according to the present invention, even when the storage temperature is relatively high, formation of a primer having a specific composition on the metal material can be remarkably monitored as a function of time.

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148746 16

Therefore, the finished adhesive assembled can prepared using the present primer is particularly suitable as a can which is subjected to retort sterilization treatment at high temperatures, e.g. a sterilization treatment carried out at a temperature of 122-135 ° C for 10-150 minutes under a pressure of 1.1-2.3 kg / cm (pressure gauge). That is, the finished sticky can is extremely suitable as a can for preserving various beverages such as fruit juices, mixed fruit juice drinks as well as coffee, fruits, vegetables, marine products, meat products and processed foods. Of course, the above advantages can also be obtained when the finished adhesive-assembled can is used as a can subjected to a heat sterilization treatment -15 at a temperature lower than the temperature of the above-mentioned high temperature sterilization process, e.g. a sterilization treatment at 110-121 ° C, or a can in which the contents are filled in hot state, e.g. at the boiling temperature.

The invention is explained in more detail in the following examples, which serve solely to illustrate the invention and not to limit its scope.

Example 1 25 This example illustrates the effect of the types and amounts of the divalent phenol and monovalent phenol in a mixed phenol used to prepare a resole-type phenol aldehyde resin on the effects of the finished adhesive cans.

30 The metal plate used as a metal material is a chromic acid treated steel plate having a thickness of 0.24 mm ("Hi-Top" from Toyo Kohan).

As the adhesive, a linear polyamide derived from 12-aminolauric acid and having a viscosity fraction 35 of 2.7, measured in a 1% solution in 98% concentrated sulfuric acid, is used.

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17 148746 /

The primer is prepared as follows.

A 3.7% aqueous formaldehyde solution is added to a mixed phenol of the composition listed in Table I. 2.0 moles of formaldehyde are used per day. moles of mixed phenol. Then the temperature is raised to 65 ° C to dissolve the mixed phenol in the aqueous solution. Then, a basic catalyst (magnesium hydroxide) is added to the solution and the reaction is carried out at 95 ° C for several hours. The reaction product is extracted with a mixed solvent containing a ketone, an alcohol and a hydrocarbon which is washed with water. Then the water is removed by azeotropic distillation or precipitation.

The phenol aldehyde resin thus produced has a number average molecular weight of 250-500.

The resulting solution of the phenol aldehyde resin type resin is mixed with a solution prepared separately by dissolving an epoxy resin having a number average molecular weight of 3750 ("Epikote 1009" from Shell Chemicals) in a mixed solvent containing a ketone, an ester , an alcohol and a hydrocarbon. The weight ratio of the epoxy resin / phenol aldehyde resin mixture is 75/25. The resulting mixture is heated at reflux (110 ° C) to perform pre-condensation. In this way, the primer is prepared.

The primer prepared is applied to both surfaces of the above steel plate ("Hi-Top") and cured at 150-230 ° C for from 1 to 20 minutes to form a cured coating layer of 30 l-15 µm thickness.

The coated metal plate is cut to produce a canister of 78.3 mm in diameter and an inner volume of 454.4 ml, and the cut plate is rounded by three rollers. Then a strip of the above polyamide adhesive having a thickness of approx. 100 µ u and width of approx. 8 mm between the upper 148748

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18 patchy side edges to be glued together. The side edges of the rounded plate to be glued are heated to 230 ° C, pressed together for approx. 50 milliseconds, then cool and a metal can body is obtained. The seam-5 width of the adhesive-bonded part is 5 mm.

A lid is double folded to one opening in the bracketed frame, and another lid is double folded to the other opening. Then, the filled can is subjected to heat treatment at 125 ° C for 60 minutes.

10 This heat treatment test is carried out with 20 canisters for each primer. The cans are examined for the presence or absence of fractures and the peel strength of the adhesive assembled is measured at 25 ° C before and after the heat treatment, furthermore the peel strength is measured at 25 ° C for the adhesive assembled after storage for 6 months, 1 year or 2 years at 37 ° C. The results obtained are given in the following Table I.

It is clear from the results in Table I that by using various divalent phenols and mono-phenols encompassed by the invention, good strengths of the adhesive assemblies are obtained both before and after heat treatment at 125 ° C for 60 minutes. and in subsequent storage for a long time, provided that the mixing ratio of divalent to monovalent phenol is within the range of 98/2 - 65/35 (according to the invention), as is the case in Experiments 1-15.

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21 148746

Example 2

This example illustrates the effect of the mixing ratio of the divalent phenol to the monovalent phenol in a mixed phenol used in the preparation of a phenol aldehyde resin-type resin on the properties of the finished adhesive assembled can.

As divalent phenol, 2,2-bis (4-hydroxy-phenyl) propane (bisphenol A) is used, and as the monovalent phenol p-cresol is used. The weight mixing ratio is given in the following Table II.

By analogy to the procedure described in Example 1, a resole-type phenol aldehyde resin having a number average molecular weight of 200-450 is prepared from the above mixed phenol. An epoxy resin having a number average molecular weight of 2650 ("Epikote 1007" from Shell Chemicals) is mixed with the phenol aldehyde resin prepared above. The weight mixing ratio of epoxy resin to phenolaldehyde resin is 75/25.

Using the 20 primer thus prepared, an adhesive-cans can be prepared in the same manner as described in Example 1. The metal plate used and the polyamide adhesive used are the same as used in Example 1. The adhesive-assembled can produced is tested in the same manner as described in Example 1 , 25 and the results obtained are listed in the following Table II.

It is evident from the results in Table II that when the mixing ratio of divalent phenol to monovalent phenol is outside the range 98/2 - 65/35 (according to the invention), as is the case in Experiment 1 (100/0), Experiment 7 (60/40), Experiment 8 (50/50), Experiment 9 (30/70) and Experiment 10 (10/90), cans break after heat treatment at 125 ° C for 60 min, whereas this does not occur. is the case in the range 98/2 - 65/35 (except 35 except for trial 2 where a single rupture occurs). Than-

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Furthermore, it is seen that the strength of the adhesive collection falls significantly outside the range 98/2 - 65/35, both in the heat treatment itself and in subsequent storage, whereas this is not the case in the interval 98/2-5 65/35.

The mixing ratios of Experiments 8-10 fall within the range of 50/50 - 90/10 used in U.S. Patent No. 3,663,354.

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25 148746

Example 3

This example illustrates the effect of the mixing ratio of the phenol aldehyde resin-type resin and the epoxy resin in a primer on the properties of the finished adhesive assembled can.

The resole-type phenol aldehyde resin is prepared by reacting a mixed phenol containing 80% by weight 2,2-bis (4-hydroxyphenyl) butane (bisphenol B) and 20% by weight o-cresol with a 37% aqueous formaldehyde solution in the presence of a basic catalyst. The amount of formaldehyde is 2.5 moles per moles of mixed phenol. The number average molecular weight of the final phenol aldehyde. resole type resin is 350.

The phenol aldehyde resin thus prepared is mixed with the same epoxy resin as used in Example 1 in the mixing ratio given in Table III. Using the primer thus prepared, an adhesive-collected can is prepared in the same manner as described in Example 1. The same metal plate type 20 and polyamide adhesive as used in Example 1. The finished adhesive-collected can is tested in the same manner as described in Example 1, and the obtained results are given in the following Table III.

The results in Table III show that the adhesive assemblies are durable only after heat treatment at 125 ° C for 60 minutes when the above mixing ratio is between 95/5 and 50/50 (Experiments 2-6), which is a prerequisite for the invention, but not an inventive feature thereof.

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27 148746

Example 4

This example illustrates the effect of the number average molecular weight of the epoxy resin in a primer on the properties of the finished adhesive can.

The same phenol aldehyde resin used in Example 3 is mixed with an epoxy resin with the number average molecular weight given in the following Table IV to prepare a primer. In the same manner as described in Example 1, an adhesive-collected can is prepared using the primer thus prepared. The same metal plate and polyamide adhesive are used as used in Example 1. The manufactured adhesive-assembled cans are tested in the same manner as described in Example 1, and the results obtained are set forth in the following Table IV.

It is evident from the results in Table IV that the adhesive assemblies are durable only after heat treatment at 125 ° C for 60 minutes. and subsequent storage for a long time when the number average molecular weight of the epoxy resin is between 800 and 5500 (Experiments 2-7), which is a prerequisite of the invention, but not an inventive feature thereof.

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29 148746

Example 5

This example illustrates the effect of the number average molecular weight of the phenol aldehyde resin type resin in a primer on the properties of the finished adhesive cans.

A 37% aqueous formaldehyde solution is added to a mixed phenol consisting of 75% by weight of 2,2-bis- (4-hydroxyphenyl) propane (bisphenol A) and 25% by weight of p-cresol. The amount of formaldehyde is 2.0 moles per ml. mole 10 of mixed phenol. The temperature of the mixture is raised to 65 ° C to dissolve the mixed phenol in the aqueous solution. Then 25% ammonia water is added to the solution. The amount of ammonia is 0.1 mol. moles of mixed phenol. The reaction is carried out at 95 ° C for 10 minutes to 8 hours to form a resole-type phenol aldehyde resin having a number average molecular weight as set forth in Table V. The phenol aldehyde resin thus prepared is mixed with an epoxy resin having a number average molecular weight of 3750 ("Epic"). Chemicals) to form a primer. The epoxy resin / phenol aldehyde resin blend ratio is 80/20 by weight. In the same way as described in Example 1, an adhesive collected can is prepared using the primer thus prepared. The same type of metal plate and polyamide adhesive are used as used in Example 1. The adhesive collected can is tested in the same manner as described in Example 1, and the results obtained are given in Table V below.

The results in Table V show that when the 30 average molecular weight is below 200 (190 in Experiment 1) or above 1000 (1040 and 1400 in Experiments 8 and 9), the cans break after heat treatment at 125 ° C for 60 minutes. whereas this does not occur when the number average molecular weight is in the range 200-35 -1000 (according to the invention).

o 148746 30

Furthermore, it is evident that the strength of the adhesive collection is itself relatively low outside the range 200-1000.

Moreover, it can be seen that the adhesive bonding strength 5 is well maintained by long-term storage after the heat treatment in the case of primers according to the invention.

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32 U8746

Example 6 37% aqueous formaldehyde solution is added to a mixed phenol consisting of 85 wt.% 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and 15 wt.% O-cresol. 2.0 moles of formaldehyde are used per day. moles of mixed phenol. The temperature of the mixture is raised to 65 ° C to dissolve the mixed phenol in the aqueous solution. Then 25% ammonia water is added to the solution and the reaction is carried out at 95 ° C for 3 hours. The amount of ammonia-10 is 0.1 mole per moles of mixed phenol.

The condensation product formed is extracted with a mixed solvent consisting of 30 parts of methyl isobutyl ketone, 20 parts of cyclohexanone and 50 parts of xylene and washed with water. The water is removed by precipitation.

The solution of phenol-aldehyde resin thus prepared has a solids content of 30% by weight, and the resin has a number average molecular weight of 375.

Separately, an epoxy resin having a number average molecular weight of 3750 ("Epikote 1009" from Shell Chemicals) is dissolved in the same type of mixed solvent as used above.

The two solutions are mixed to form a solution having a solids content of 33% and having a weight ratio of epoxy resin to phenolaldehyde resin of 75/25. The solution is heated to 110 ° C for 3 hours to effect pre-condensation, thus forming a primer in the form of one. resolution.

30 A piece of metal plate is cut into a canister of 74 mm diameter and an internal volume of 318.2 ml from a 0.23 mm thick chromic acid treated steel plate ("Hi-Top" by Toyo Kohan) and the the above-made primer is applied to both surfaces of the plate at a thickness of about 5 °, u, then cure at 205 ° C for 10 minutes.

33 148746

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A strip of poly-12-aminolauric acid having a thickness of 50 µ, 11, a width of 8 mm and a viscosity fraction of 2.3 is applied to both side edges of the coated sheet material to be adhered and the strip 5 is compressed at 230 ° C. 2 seconds and cool. The resulting sheet with a polyamide coating on both side edges is formed by three rollers so that the polyamide coated surfaces abut. The polyamide-coated surfaces are then overlapped, heated for 50 milliseconds by high-frequency heating, compressed and cooled, and a can body is obtained.

The peel strength of the crease on the sticky can body is 24 kg / cm. A lid is double-folded to one can of the can body, and hot water at a temperature of 95 ° C is filled into the can, and a second lid is double-folded to the other opening.

The filled can is subjected to a heating treatment at 130 ° C for 60 minutes and no cans of breakage are found among the 1000 tested cans. The peel strength of the adhesive collected part after the heat treatment is 22 kg / cm measured at 20 ° C. The peel strength of the adhesive compartment after storage for 6 months, 1 year and 2 years at 37 ° C is respectively. 20, 18 and 13 kg / cm measured at 20 ° C. In no case is a breakage 25 of the adhesive collected part and a good vacuum condition is maintained in the can, the internal pressure being at least 40 cm Hg less than the atmospheric pressure.

Example 7 An primer is prepared by analogy to the procedure described in Example 6 with the following exceptions. As a mixed phenol, a mixture consisting of 90% by weight of bis (4-hydroxyphenyl) methane (bisphenol F) and 10% by weight of p-tert.-butylphenol is used, and 35 as a catalyst sodium carbonate is used in an amount of 0.01 mol per liter. moles of mixed phenol. number average

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The molecular weight of the phenolaldehyde resin formed is 320. An epoxy resin having a number average molecular weight of 2650 ("Epikote 1007" from Shell Chemicals) is used as the epoxy resin. The mixing ratio of epoxy-5 resin to phenolaldehyde resin is 70/30 by weight. The pre-condensation is carried out at 110 ° C for 5 hours.

The primer is applied to the two sides of a degreased cold rolled steel plate and cured at 210 ° C for 10 minutes. In the same way as described in Example 6, a can body is prepared using a film of poly-6-aminocaproic acid having a viscosity fraction of 2.25 as a linear polyamide adhesive. The peel strength of the adhesive assembly is 26 kg / cm measured at 37 ° C. A lid is double folded on one opening in the can body and 15 hot water at a temperature of 95 ° C is filled into the can, after which a lid is double folded on the other opening.

The filled stock is subjected to heat treatment at 125 ° C for 90 minutes. No canned body rupture is found - but in this heat treatment. The peel strength of the adhesive collected portion after the heat treatment is 22 kg / cm measured at 20 ° C. The peel strengths of the adhesive compartment after storage for 6 months, 1 year and 2 years at 37 ° C are, respectively. 19, 16 and 13 kg / cm measured at 20 ° C. In no case is the breakage of the adhesive collected part 25 and a good vacuum condition is maintained in the can, the internal pressure being at least 40 cm Hg less than the atmospheric pressure.

Example 8 Lids are double-folded to one opening of canned carpets made using the primers prepared in Example 1, and hot water at a temperature of 95 ° C is filled into the cans, after which lids are double-folded to the other opening. The finished filled cans are then subjected to heat treatment at 115 ° C for 60 minutes. The number of canned pieces that break

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35 148746 at the heat treatment, checked. After the heat treatment, the filled cans are left at room temperature for 1 week or stored for 1 year, and the internal vacuum [atmospheric pressure (76 cm Hg) - internal pressure (cm Hg absolute)] in the cans is determined in order to determine the leakage briefly. after the heat treatment and after a long period of storage. The results obtained are listed in the following Table VIII, where the trial numbers correspond to those listed in Table I.

10

Table VIII

Pore Number of cans Internal vacuum Internal vacuum Remarks Search with break by in can after in can after no heat treatment 1 week storage 1 year storage at 115 ° C (cm Hg) ring (cm Hg) for 60 minutes ( n = 20) (n = 20) 15 (n = 100) 10 45 42 Iflg. opf.

20 44 41 40 46 42 20 6 0 47 43 7 0 48 44 80 45 42 "10 0 46 43 12 0 45 42" 25 13 0 44 42 "16 0 40 5 Comparison 17 0 38 0" 18 0 35 0 "1 2 3 4 5 6

Example 9 2 Lids are double-folded on one opening in the adhesive 3 total canisters made using 4 primers made according to example 2, and 5 hot water with a temperature of 95 ° C is filled into the cans.

6

Then the lid is double folded on the second opening and the filled cans are heat treated at 115 ° C for 60 minutes. Quantity-

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Light from canned bones with a fracture caused by this heat treatment is found. After the heat treatment, the filled cans are stored for 1 week or 1 year, and the internal vacuum (cm Hg) is determined for examination of 5 leaks shortly after the heat treatment and a long time after the heat treatment. The results obtained are shown in the following Table IX, where the trial numbers correspond to those listed in Table II.

Table IX

Pre- Number of cans Internal vacuum Internal vacuum Remarks Search with canister in can after in can after no heat treatment 1 week storage 1 year storage at 115 ° C (cm Hg) ring (cm Hg) for 60 minutes ( n = 20) (n = 20) (n = 100) 15 - 1 0 40 0 Comparison 20 45 40 According. opf.

3 0 47 43 40 46 44 "20 5 0 48 44 6 0 45 41 7 0 42 20 Comparison 80 40 10" 9 0 38 5 25 10 0 38 3

Leakages caused by vigorous sterilization (retort sterilization) of canned bodies are classified as follows: (1) Canned body rupture: When the bonding forces are greatly diminished in the area along the lateral rim by vigorous sterilization, the can body breaks into the lateral seam during vigorous sterilization and the contents seep out .

(2) Microdensity: When the bond strength decreases in some places in the bonding interface along the side seam, although the above mentioned

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If the canister is not broken, micro-leakage occurs from such points after vigorous sterilization.

(3) Late onset leakage: 5 Although no leakage occurs shortly after heavy sterilization treatment in the area near the double-folded portion of the side seam, the bond between the metal material and primer will become insufficient over time as a result of treatments and heavy sterilization. In this case, gradual leakage occurs during prolonged storage.

In the case of sticky cans, using a primer containing a phenol formaldehyde resin made from a mixed phenol in which the amount of dicyclic phenol is outside the scope of this invention and an epoxy resin, it is possible to perform heat sterilization (does not cause canned body) when the temperature is relatively low, e.g. 115 ° C, but it is clear from the results given in Tables 20 and VIII that micro-leakage and subsequent leakage are significant in these cases. In the case of adhesive-assembled can wraps made using the aforementioned primers, visible rupture of the can bodies occurs when the sterilization temperature is high, e.g. 125 ° C.

When adhesive-assembled cans are prepared using a primer containing a phenol-formaldehyde resin formed using a mixed phenol in which the amount of the dicyclic phenol is within the range and an epoxy resin, no micro-leakage or subsequent leakage occurs and these cans are sufficiently resistant to withstand heat sterilization at temperatures as high as 125 ° C.

35

Claims (4)

An adhesive-assembled can body that can withstand retort sterilization, consisting of a metal plate having the two opposite side edges adhered to a linear polyamide adhesive through an epoxy phenol resin primer containing 50 to 95 weight percent of an epoxy resin having a number average molecular weight 800 5500, which is made by condensing an epihalohydrin with bisphenol A, and 5 to 50% by weight of a phenol aldehyde resin of the 10 resole type, characterized in that the resole type phenol aldehyde resin has a number average molecular weight of 200-1000 and is produced by reaction of a mixed phenol containing 65-98% by weight of a divalent phenol of the general formula I wherein R is a group of the formula -CR R -, wherein R and R are hydrogen or an alkyl group having up to 4 carbon atoms, a group -O- or a direct bond, and 2-35% by weight of a monovalent phenol selected from unsubstituted phenol or phenol su substituted with 1 or 2 alkyl groups 25 with up to 6 carbon atoms or with a phenyl group, with formaldehyde in the presence of a basic catalyst. The adhesive assembled can empty according to claim 1, characterized in that the divalent phenol is 2,2-bis (4-hydr, oxyphenyl) propane or 2,2-bis (4-hydroxyphenyl) butane. Adhesive canned body according to claim 1, characterized in that the divalent phenol (a) and the monovalent phenol (b) in the resolol phenol aldehyde resin are in weight ratios of (a) to (b) of from 95/5 to 75/25 . The adhesive-assembled can body according to claim 1, characterized in that the resolol-type phenolaldehyde resin is a resin having a number average molecular weight of