DK148040B - PROCEDURE FOR MANUFACTURING LIMITED PAPER AND LIMITING MEASURES FOR USING THE PROCEDURE - Google Patents

Description

U8040

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for making glue paper using an aqueous emulsion comprising a hydrophobic, cellulose-reactive sizing agent in the form of a ketene dimer, an acid anhydride or organic isocyanate, an emulsifier and a sizing accelerator, and optionally a small amount of sodium. -ligninsulfonat

The process is also applicable to the manufacture of glued cardboard.

From the disclosure of U.S. Patent No. 3,840,486, water-soluble heat-curing resin compositions are obtained from the reaction of dicyanamide, an ammonium salt, formaldehyde and an acid salt of a water-soluble aminopolyamide, such as the water-soluble aminopolyamide, obtained by reaction between adipic acid and adipic acid. The resin compositions known from U.S. Pat. No. 3,840,486 speed up the sizing provided with reactive cellulose sizing agents such as ketene dimers, acid anhydrides and isocyanates. Using the resin compositions as disclosed in U.S. Patent No. 3,840,486 in combination with said paper sizing agents, provides increased sizing after the machine in relation to what is achieved by using equivalent amounts of the sizing agent alone.

From the disclosure of English Patent No. 1,373,788, the use of dicyandiamide formaldehyde condensates is known as bonding accelerators for ketene dimer adhesives.

From U.S. Pat. No. 3,409,500, there is known a process for making adhesive paper in which a separate addition of an aqueous anionic dispersion of hydrophobic, organic, cellulose-reactive, paper-glueing carboxylic anhydride particles to an aqueous suspension of cellulose paper-making fiber and aqueous suspension is made. , self-sufficient cellulose-fixing cationic polyamine having a molecular weight above 1000, wherein the amount of the polyamine is at least sufficient to deposit the anhydride particles on the fibers and accelerate the rate at which the anhydride develops its bonding properties to the cellulose fibers at 88-121 ° C, spreading to form a wet-laid paper web and dry the paper web at a temperature between 88 and 121 ° C.

From U.S. Patent No. 3,666,512, compositions comprising hydrophobic, cellulose-reactive carboxylic anhydride paper sizing agents and a catalyst are known which accelerate the rate at which the anhydride develops its sizing properties when deposited on cellulose from an aqueous medium and heated. The anhydride bonding catalyst or promoter is a water-soluble cationic salt of a self-sufficient, cellulose-fixing, water-soluble polyamine. Suitable cationic agents are given in the table in column 7 of the aforementioned printing press. Among the cationic agents is an aminopolyamide epichlorohydrin resin, wherein the aminopolyamide is prepared from diethylenetriamine and adipic acid. However, this bonding accelerator is not as efficient as could be desired, cf. subsequent comparative example 19.

US Patent No. 3,923,745 discloses a cationic paper sizing resin which is prepared by reacting a diallyl amine polymer with a ketene dimer to form a reaction product which is then reacted with epichlorohydrin under reflux for 15 to 20 minutes. The constituent components are thereby reacted with each other by actual chemical reactions and the ketene dimer is consumed such that after the reaction it is no longer free and therefore no longer able to act as a hydrophobic cellulose-reactive sizing agent. Similarly, the diallylamine polymer and epichlorohydrin are also directly chemically bonded to the finished resin. The resin is said to be thermoset and its paper-bonding properties are stated to be exposed to heat after it has been applied to a paper product.

Thus, the prior art of U.S. Patent No. 3,923,745 does not solve the problem associated with the use of paper adhesives of the type with cellulose-reactive adhesives, such as ketene dimers, acid anhydrides and organic isocyanates, which consist in the fact that with these adhesive types no significant bonding is achieved in the paper until after it has been dried and naturally aged. However, this problem is solved by the present invention to such an extent that the paper, while still on the papermaking machine and leaving it, achieves a bonding level which constitutes a substantial portion of the final level reached by natural aging, cf. Example 19.

This is achieved by the fact that the process according to the invention is characterized in that as a sizing accelerator a poly (diallylamine) epihalohydrin resin is used, in sufficient quantity to increase the sizing effect of the sizing agent after the machine.

The invention also relates to a cellulose fiber sizing agent in the form of an aqueous emulsion comprising a hydrophobic cellulose reactive sizing agent in the form of a ketene dimer, anhydride or organic isocyanate, an emulsifier and a sizing accelerator, and optionally a minor amount of sodium lignin sulfate which that the sizing accelerator is a poly (diallylamine) epihalohydrin resin and is present in sufficient quantity to increase the sizing properties of the sizing agent after the machine.

The sizing accelerators used in the present invention are poly (diallyl) epichlorohydrin resins, such as e.g. is disclosed in U.S. Patent No. 3,700,623.

4 148040

The poly (diallylamine) epihalohydrin resins used in the present invention comprise the resinous reaction product of (A) a linear polymer having units of the formula

\ / CH2 / R

-H, C-C 2 -C 2 in 1 «> H-C CHO 2 2 R 'where R is hydrogen or lower alkyl and R' is hydrogen, alkyl or a substituted alkyl group and (B) an epihalohydrin.

In the above formula, the R substituents may be identical or different and, as mentioned, be hydrogen or lower alkyl. The alkyl groups contain from 1 to 6 carbon atoms and are preferably methyl, ethyl, isopropyl or n-butyl. R 'in the formula represents hydrogen, alkyl or substituted alkyl groups. The R'-alkyl groups will contain from 1 to 18 carbon atoms (preferably from 1 to 6 carbon atoms) such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl and octadecyl. R 'may also be a substituted alkyl group. Suitable substituents generally include any group which will not generate polymerization over a vinyl double bond. Typically, the substituents may be carboxylate, cyano, ether, amino (primary, secondary or tertiary), amide, hydrazide and hydroxyl.

Polymers with units of the above formula can be prepared by polymerizing the hydrohalide salt of a diallylamine CH0 CH0 II 2 II 2 R-C C-R (II)

I I

CH

XN

R 'wherein R and R' are as defined above, either alone or in admixture with other copolymerizable constituents in the presence of a free radical catalyst and then neutralizing the salt to form the free base of the polymer.

Particular hydrohalide salts of the diallylamines which can be polymerized to provide the polymers for use in the invention include diallylamine hydrochloride, N-methyldiallylamine hydrobromide, 2,2'-dimethyl-N-methyldiallylamine hydrochloride, N-ethyldiallyl amine hydrochloride isopropyldiallylaminhydrochlorid, Nn-butyldiallyl-hydrobromide, N-tert-butyldiallylaminhydrochlorid, Nn-hexyldiallylaminhydrochlorid, N-octadecyldiallylaminhydrochlorid, N-acetamidodial-lylaminhydrochlorid, N-cyanmethyldiallylaminhydrochlorid, N-3-propionic amidodiallylaminhydrobromid, N-carboethoxymethyldiallylaminhydrochlorid, Ν-β-methoxyethyldiallylaminhydrobromid, Ν-β-Aminoethyldiallylamine hydrochloride, N-hydroxyethyldiallylamine hydrobromide and N-acetohydrazide substituted diallylamine hydrochloride.

In the preparation of the homopolymers and copolymers for use in the present invention, reaction can be initiated by a catalytic redox system. In a redox system, the catalyst is activated by a reducing agent which forms free radicals without the use of heat. Commonly used reducing agents are sodium metabisulfite and potassium metabisulfite. Other reducing agents include water-soluble thiosulfates and bisulfites, hydrosulfites, and reducing salts, such as the sulfate of a metal capable of existing on more than one valence stage, such as cobalt, iron, manganese and copper. A particular example of such a sulfate is ferrous sulfate. The use of a redox initiator system has several advantages, the most significant of which is efficient polymerization at lower temperatures. Usual peroxide catalysts, such as tert-butyl hydroperoxide, potassium persulfate, hydrogen peroxide and ammonium persulfate, used in connection with the aforementioned reducing agents or metal activators may be used.

As indicated above, the linear polymers of diallyl amines may contain various units of formula (I) and / or contain units of one or more other copolymerizable monomers. The comonomer is typically another diallylamine, a monoethylenically unsaturated compound containing a single vinyl or vinylidene group or sulfur dioxide and is present in an amount of from 0 to 95 mole percent of the polymer. Thus, the polymers of diallylamine are linear polymers wherein from 5% to 100% of the repeating units have formula (I) and from 0 to 95% of the repeating units are monomeric units derived from (1) a vinyl or vinylidene monomer and / or (2) sulfur dioxide. Preferred comonomers include acrylic acid, methacrylic acid, methyl and other alkyl acrylates and methacrylates, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl ethers such as alkyl vinyl ethers, vinyl ketone, vinyl ketone or ethyl vinyl ketone, ethyl vinyl ketone, which falls under the above formula (II).

Particular copolymers which can be reacted with an epihalohydrin include copolymers of N-methyldiallylamine and sulfur dioxide, copolymers of N-methyldiallylamine and diallylamine, copolymers of diallylamine and acrylamide, copolymers of diallylamine and acrylic acid, copolymers of N of diallylamine and acrylonitrile, copolymers of N-methyldiallylamine and vinyl acetate, copolymers of diallylamine and methyl vinyl ether, copolymers of N-methyl-diallylamine and vinylsulfonamide, copolymers of N-methyldiallylamine and methylvinyl ketone, terpolymers of diallylamine and sulfur , acrylic acid and acrylamide.

The epihalohydrin reacted with the polymer by a diallylamine can be any epihalohydrin, i.e. epichlorohydrin, epibromohydrin, epifluorohydrin or epiiodhydrin and is preferably epichlorohydrin. Generally, the epihalohydrine is used in an amount of from about. 0.5 mol to approx. About 1.5 moles and preferably from ca. 1 mole to approx. 1.5 moles per moles of secondary plus tertiary amine present in the polymer.

The poly (diallylamine) epihalohydrin resin can be prepared by reacting a homopolymer or copolymer of a diallylamine as set forth above with an epihalohydrin at a temperature of between about 30 ° C and approx. And preferably between about 80 ° C. 40 ° C and approx. 60 ° C until the viscosity measured on a solution containing 20-30% solids at 25 ° C has reached a size between A and E and preferably around C-D according to the Gardner-Holdt scale. The reaction is preferably carried out in aqueous solution to moderate the reaction and at a pH of from ca. 7 to approx. 9.5.

When the desired viscosity is reached, sufficient water is added to adjust the solids content of the resin solution to approx. 15% or less and the product is cooled to room temperature (about 25 ° C).

The resin solution may be stabilized against gel formation by adding to the aqueous solution thereof of sufficiently highly water-soluble acid (such as hydrochloric or sulfuric acid) that the pH is adjusted to and maintained at about 2. The resulting acid stabilized resin solution may be used as such in the practice of the invention. or, if desired, reactivated in known manner prior to use. Such acid stabilized resin solutions and reactivating agents thereof are disclosed in the specification of U.S. Patent No. 3,833,531.

7 U8040

Before stabilizing against gelling, the resin in the active or cross-linkable active form may be reproduced as follows: CH9 \ H2C_f C | "(III) H2 \ VH2 \ N / R 'NCHoCHCH0 2V 2

ISLAND

After stabilization against gelling, e.g. with HCl, becomes -CHOCHCH «

2 \ / 2 O

in (III) to -CH-CHCH- (IV), where X is halogen such as chlorine. After re / I 2

OH X

activation of the resin by adding aqueous NaOH to the resin solution returns (IV) to the epoxide form shown in (III).

-CHOCHCH- i (III) can, if desired, be converted to -CHOCHCHO 2 \ / 2 2 / i 2

O OH OH

(V) by adding sodium bicarbonate to the solution of (III) and heating the resulting solution to ca. 100 ° C for 1-1 / 2 hours. In form (V), the resin will not crosslink and cannot be returned to (III). It is in glycol form and is an inert cationic polymer.

All forms of the resin shown above can be used in the present invention, and the term poly (diallylamine) epihalohydrin resin includes - used in this specification and claims - all resins wherein the epihalohydrine moiety resides on the one in (III), (IV) and (V). The resin used in the invention can thus be reproduced as follows: CHO

\ / \ / E

-H-C-C C- 1 © I (vi) H2C ^ N ^ H2 κ \

R 'E

wherein E is -CH9CHCH9, -CH9CH CH9 or -CHOCH CH0.

2 \ / 2 2 | I 2 2 | I 2

0 OH Cl CH OH

8 1-48040

The following examples illustrate the preparation of the poly (diallylamine) epichlorohydrin resins used in the present invention. In the examples, the parts indicated are all parts by weight.

Example 1

A solution of 69.1 parts of N-methyldiallylamine and 197 parts of 20 ° Hydrochloric acid in 111.7 parts of demineralized water was passed through nitrogen to remove air, then treated with 0.55 parts of tert-butyl hydroperoxide and a solution of 0.0036 parts ferrous sulfate in 0.5 parts water. The resulting solution was allowed to polymerize at 60-69 ° C for 24 hours to form a polymer solution containing ca. 52.1% solids with an RSV value of 0.22. 122 parts of the above solution were adjusted to pH 8.5 by the addition of 95 parts of 3.8% sodium hydroxide and then diluted with 211 parts of water and combined with 60 parts of epichlorohydrin. The mixture was heated to 45-55 ° C for 1.35 hours until the Gardner-Holdt viscosity of a sample, cooled to 25 ° C, reached B +. The resulting solution was acidified with 25 parts of 20 ° B hydrochloric acid and heated to 60 ° C until the pH became constant at 2.0. The resulting resin solution had a solids content of 20.8% and a Brookfield viscosity of 77 cp (measured using a Brookfield Model LVF viscosimeter with a No. 1 spindle and a controlled speed of 60 cm / hr.}

Example 2 Twenty-five parts of a 9.58% solids resin solution prepared according to Example 1 was combined with a solution of 1.62 parts of 10 N sodium hydroxide in 11.25 parts of water and matured for 0.5 hour.

Example 3 150 parts of a 20% solids resin solution prepared according to Example 1 were diluted with 172.5 parts of water. To the solution was then added a solution of 7.2 parts of NaOH in 160 parts of water. The resulting solution was allowed to stand for 5 minutes and then 10.5 parts of NaHCO 3 was added. The solution was then heated to reflux and refluxed for 1.5 hours. and then cooled to room temperature. The resulting solution had a solids content (modified resin) of 9.2% and a Brookfield viscosity of 77 cP (measured using a Brookfield Model LVF viscometer with a No. 1 spindle and a controlled speed of 60 rpm. /mine.).

The sizing accelerators for use according to the invention are used in combination with hydrophobic, cellulose-reactive sizing agents such as ketene dimers, acid anhydrides and isocyanates. These sizing agents are well known in the art and are usually used as aqueous emulsions. The term "emulsion" is used herein, as is customary in the art, in the sense of either a liquid-in-liquid type or a solid-in-liquid type dispersion.

Hydrophobic acid anhydrides useful as cellulose-reactive sizing agents for paper include (A) natural resin anhydrides such as rosin anhydrides, cf. the specification of patent No. 3,582,464, (B) anhydrides of structure 0, /

R-C

\ (VII) 0 R1- / \

ISLAND

is a saturated or unsaturated hydrocarbon radical, wherein the hydrocarbon radical is a straight or branched alkyl radical, an aromatic substituted alkyl radical or an alkyl substituted aromatic radical, as long as the hydrocarbon radical contains a total of about

14 to 36 carbon atoms, and (C) cyclic dicarboxylic anhydrides of the structure

ISLAND

II

R | _R, I o (VIII)

II

wherein R 1 'represents a dimethylene or trimethylene radical and wherein R 1 is a hydrocarbon radical containing more than 7 carbon atoms selected from the group consisting of alkyl, alkenyl, aralkyl or aralkenyl. Substituted cyclic dicarboxylic anhydrides encompassed by the above formula (VIII) are substituted succinic and glutaric anhydrides. In the above formula (VII), all of the R 2 substituents may be the same hydrocarbon radical or different hydrocarbon radicals.

Particular examples of anhydrides of formula (VII) are myristoyl anhydride, palmitoyl anhydride, oleoyl anhydride and stearoyl anhydride.

Particular examples of anhydrides of formula (VIII) are isooctadecenyl succinic anhydride, n-hexadecenyl succinic anhydride, dodecyl succinic anhydride, decenyl succinic anhydride, octenyl succinic anhydride and heptyl glutaric anhydride.

Hydrophobic organic isocyanates used as adhesives for paper are well known in the art. The best results are obtained when the hydrocarbon chains of the isocyanates contain at least 12 carbon atoms, preferably 14-36 carbon atoms. Such isocyanates include resin isocyanate, dodecyl isocyanate, octadecyl isocyanate, tetra-decyl isocyanate, hexadecyl isocyanate, eicosyl isocyanate, docosyl isocyanate, 6-ethyldecyl isocyanate, 6 isocyanate radicals and impart hydrophobic properties to the molecule as a whole.

Ketene dimers used as cellulose-reactive sizing agent are well known in the art and are dimers of the formula {R2CH = C = O] 2 (IX) 2 where R is a hydrocarbon radical such as alkyl of at least 8 carbon atoms, cycloalkyl of at least 6 carbon atoms, aryl, aralkyl and alkaryl .

When naming chain dimers, "R" is followed by "chain dimer". Thus, phenyl ketene dimer <+ - ^) - CH = C = 0 L - - \ 2 benzyl ketene dimer: (3-ch 2 -ch = c = ° l_ - 2) and decyl ketene dimers: [CjqH2j-CH = C = 0] 2 · Examples of ketene dimers include the octyl, decyl, dodecyl, tetradecyl / hexadecyl, octadecyl, eicosyl, docosyl / tetracosyl, phenyl, benzyl, beta-naphthyl and cyclohexylketene dimers and the ketene dimers of the ketene dimers. .: montamic acid), naphthenic acid, Δ9,10-decylenic acid, Δ9,1u-dodecylenic acid, palmito-oleic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid and eleostearic acid, and ketene dimers made from naturally occurring mixtures of fatty acids, such as mixtures of fatty acids, such as mixtures of fatty acids, , palm kernel oil, palm oil, olive oil, peanut oil, rapeseed oil, beef tallow, blubber and whale blend, mixtures of any of the above fatty acids with other of these may also be used.

The following examples show the preparation of ketene dimer emulsions.

Example 4

An emulsion of an alkyl ketene dimer prepared from a mixture of palmitic acid and stearic acid was prepared by mixing 880 parts water, 60 parts cationic corn starch and 10 parts sodium lignin sulfonate. The pH of the mixture was adjusted to approx. 3.5 with 98% sulfuric acid. The resulting mixture was heated to 90-95 ° C for approx. one hour.

Water was then added to the mixture in sufficient quantity to produce a mixture of 1750 parts (total weight). Ca. 240 parts of the key trend was stirred into the mixture along with 2.4 parts of thiadiazine. The thiadiazine was used as a preservative. The resulting premix (at 65 ° C) was homogenized by passage through a homogenizer at 282 kg / cm. The homogenized product was diluted with water to a dry content of ketene dimer of ca. 6%.

Example 5 Example 4 was repeated except that the alkyl ketene dimer of oleic acid was used in place of the alkyl ketene dimer made from a mixture of palmitic acids and stearic acids.

Example 6

A portion of the emulsion of Example 4 was diluted with water to a ketene dimer solids content of 0.10%.

Example 7 12 148040

A portion of the emulsion in Example 5 was diluted with water to a ketene dimer content of 0.10%.

Example 8

Products prepared according to Example 1 and Example 4 were combined with the addition of water as needed to form an aqueous sizing agent comprising 0/10% ketene dimer and 0/20% resin.

Example 9

Products prepared according to Example 1 and Example 4 are combined with the addition of water as needed to provide an aqueous sizing agent consisting of 0.10% ketene dimer and 0.10% resin.

Example 10

Products prepared according to Example 2 and Example 4 are combined with the addition of water as needed to provide an aqueous sizing agent containing 0.10% ketene dimer and 0.10% acid stabilized resin.

Example 11

Products prepared according to Example 3 and Example 4 are combined with the addition of water as needed to provide an aqueous sizing agent consisting of 0.10% ketene dimer and 0.10% modified resin.

Example 12

Products prepared according to Example 1 and Example 5 are combined with the addition of water as needed to provide an aqueous sizing agent containing 0.10% ketene dimer and 0.10% resin.

The above sizing agents were applied to the surface of a 2 sheet 18 kg / 279 m bucket paper. The sheet was made from a 50:50 mixture of hardwood and softwood on a pilot paper machine. The pH of each sizing agent was set to 7 prior to application to the sheet in the clamping region 148060 13 for a horizontal sizing press. The glue press operated at a speed of 12.2 m / min and the fluid uptake was 70%. The retention of the ketene dimer adhesive was the same in all these experiments. The glued sheets were dried at 93 ° C for 20 sec. on a laboratory size drum dryer for 4% humidity. The sizing was measured by "Hercules Size Test" with sample solution # 2 for the reflectance given in the tables. The test results after the machine were determined within 2 min. after drying and the test results in natural ripening after at least 3 days storage at room temperature. It is well known in the art that ketene dimer adhesives develop virtually all their bonding properties in the paper over the course of 3 days. After this point, the bonding properties of the paper remain essentially the same.

The bonding results are given in the table below.

Table I

Bonding agent _Hercules Size Test_ according to After machine to 80% Natural matured to 85%

Example reflectance (seconds) reflectance (seconds) 6) 2 separate 0 331 6) samples 0 400 7 0 554 8) 2 separate 310 350 8) samples 305 9) 2 separate 335 450 9) samples 160 436 10 437 590 11 250 500 12 315 500

The following examples show the improvements in the sizing after the machine when the sizing agents according to the invention are used for internal sizing.

2 Quality sheets of 18 kg / 279 m were made on a Noble and Wood handset using a pulp consisting of 30% waste newspapers, 35% Rayonier bleached conifer and 35% Weyer Haus bleached kraft hardwood. Sheets were dried for 45-50 seconds at 102 ° C. The sizing accelerator resin was added in aqueous solution to the sample, where the pulp density was approx. 0.275%, and stirred for 15 sequences, and then the ketene dimer adhesive emulsion followed by stirring in U8040 14 was added for another 15 seconds. This was then diluted with water to a pulp density of approx. 0.025% in the cover box before sheet formation. The amount of accelerator resin and chain dimer used is shown in Table II below and is based on the dry weight of the pulp.

The test results are shown in Table II below.

^ Hercules Size Test for 80% reflectance

Accelerator Ketene dimer resin emulsion according to After Natural

Example No. ge Example 1 Example 4_ The machine matured 13 nothing 0.15% chain 0 300 dimer 14 0.15% "16 303 15 0.30%" 78 464 16 0.45% "154 594 In Examples 14, 15 and 16. The accelerator resin and the sizing agent were added separately. It should be noted that, as with surface sizing, they can be mixed together before adding to a pulp slurry to provide a sizing agent, and glued sheets are made from the thus treated slurry.

Example 17 (Comparative Example)

An aqueous emulsion of octadecyl isocyanate sizing agent (stearyl isocyanate sizing agent) was used for the internal sizing of a hand sheet using a material of 50% hardwood and 50% softwood strength with 10% clay and 10% calcium carbonate as filler. Cationic starch was added in an amount of 35% based on the dry weight of the pulp as a retention aid for the fillers. The amount of octadecyl isocyanate used as an adhesive was 0.2% based on the dry weight of the fibers.

Example 18

Example 17 was repeated except that resin prepared according to Example 1 in aqueous solution was also added to the pulp slurry prior to sheet formation in an amount equal to 0.125% of the pulp dry weight. Test results are given in Table III below.

Table III

15 148040

Hercules Size Test for 80% Reflectance Sheets According to After Natural

Example_ the machine matured 17 18 90 18 62 75

Example 19 (sample comparison example)

Sheets of paper were prepared and surface-glued as described in Example 12 but with the combinations of sizing agent and sizing accelerator set forth in Table IV. All emulsions were freshly prepared with 25% cationic starch and 4.2% sodium lignin sulfonate as emulsion stabilizers.

Bonding results were measured as described in Example 12.

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The lining accelerators used in experiments 4-6, 10-12 and 16-18 are according to the invention. It should be noted that these sizing accelerators are capable of accelerating the sizing immediately after the machine to an extent which is in most cases of the order of 50% or more of the sizing obtained maximum by natural aging, which is far of what is obtained without the use of accelerator, Experiments 1, 7 and 13, or that obtained by using the accelerators which are not according to the invention, Experiments 2-3, 8-9 and 14-15, including that of the United States Patent No. 3,666,512 to the prior art accelerator, "Kymene 557".