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Patenting and inventive activity on synthetic fibre intermediates
329
Patenting and inventive activity on synthetic fibre intermediates P. WISEMAN Departmentof Chemistry, UMIST,
Sackville Street, Manchester
Mb0 IQD,
U.K.
Final version received April 1983
The demand-pull theory of invention and innovation has drawn much of its support from the work of Jacob Schmookler on patent time series. In this work, Schmookler found no evidence that scientific discoveries or major inventions had provided the stimulus for important inventions. However, it is argued here that his method was not well designed to detect such effects. Any effect of a particular scientific or technological development is likely to occur in a rather narrow area of technology, so that detection of science-push and technology-push will be favoured by the examination of narrow areas of inventive activity. Manufacturing processes for groups of chemical products subject to similar demand-side factors provide convenient such areas. In this study time series of patents on processes for eight intermediates for synthetic fibres have been examined. They are not consistent with a simple demand-pull theory, but rather with the view that inventive activity is affected both by demand and by technological opportunity. Two of the intermediates have been examined in detail, and evidence has been presented that in one case a major invention arose from science-push and in the other one arose from technology-push.
1. Introduction The demand-pull theory of invention and innovation which ‘received much support during the late 1960s and early 1970s has recently been extensively criticised. For example, Mowery and Rosenberg argue that much of the evidence cited in support of the theory is inconclusive [l]. Walsh et al. have also pointed to weaknesses in arguments for the demand-pull theory [2]. They noted the influential role that Schmookler has had in this field, and while acknowledging the quality of his work, suggest that it is a less compelling demonstration of the primacy of market demand in determing inventive activity than has been suggested Research Policy 12 (1983) 329-339 North-Holland 0048-7333/83/$3.00
0 1983, Elsevier Science Publishers
by Schmookler and a number of later commentators. Schmookler drew up time series of patents on inventions in four industries - agriculture, paper making, petroleum refining, and railroads - and compared them with series for investment and/or output in these industries [3]. He found that for each of these industries there were great similarities in both long term trends and long term swings between the patent and economic time series, and concluded that “(1) invention is largely an economic activity which, like other economic activities, is pursued for gain; (2) expected gain varies with expected sales of goods embodying the invention; and (3) expected sales of goods are largely determined by present capital goods sales”. Further, on the basis of examination of the historical records of major inventions he stated “Despite the popularity of the idea that scientific discoveries and major inventions typically provide the stimulus for inventions, the historical record of important inventions in petroleum refining, paper making, railroading and farming revealed not a single unambiguous instance in which either discoveries or inventions played the role hypothesized”. Walsh et al. used techniques similar to those of Schmookler to examine inventive activity in a number of sections of the chemical industry. Freeman concluded with respect to this work that their results sometimes appeared “to validate Schmookler’s results, whilst in others a counterSchmookler pattern is discernible, and in still others no clear pattern emerges” [4]. Schmookler’s approach was not in fact well designed to detect science-push effects. His patent statistics covered all inventions in the industries concerned, and the nature of the technology involved was consequently very diverse. This can clearly be seen from his appendices listing im-
B.V. (North-Holland)
portant inventions in the industries. Science-push effects in the main would be expected to arise from rather specific discoveries in a particular science, and to affect a specific sector of the technology in the industry. For example, discoveries in a particular area of chemistry might be expected to have an effect on a particular chemical refinery process, but not on other chemical processes or on all the other areas of refinery technology, such as distiIlation and solvent extraction, which do not depend on chemical phenomena. In highly aggregated data such as that used by Schmookler, changes in inventive activity on specific areas of technology will tend to be lost in the overall noise. , Effects of supply-side technical factors on inventive activity are most likely to be evident when narrow technological regions are examined. Walsh et al. examined much narrower areas than Schmookler, but a number were still broad enough to cause a substantial loss of definition in terms of effects. In this present work an attempt has been made to examine inventive activity in the chemical industry in areas narrow enough that specific effects on levels of activity can be observed. The areas chosen are concerned with process invention on selected products. 2. Process
depends on the technological opportunities for developing new or improved processes with reduced costs. The extent of these opportunities is determined (i) by the technological state of existing processes, and (ii) by the state of the relevant scientific and technological art. As the state of the art changes the extent of the opportunities may change. It is not unreasonable to expect that occasionally the changes will be such that important new opportunities suddenly become evident and major inventions will be initiated. ‘There are two major problems in trying to assess the extent to which inventive activity in the chemical industry is determined by economic or technical factors. One is that the commercial history of many of the major chemicals is relatively short, so that the identification and comparison of trends and patterns is difficult. The second is that economic data on chemical products are notoriously sparse. The approach that has been adopted here is to examine products subject to similar market factors on the supposition that ~~~~e~e~ce~ in inventive activity are likely to be due to causes other than demand-side factors. There are a number of pairs or groups of products subject to similar or identical market forces; intermediates for the manufacture of synthetic fibres form a particularly convenient group.
research and invention
The main objective of research on chemical processes is usually cost reduction. This may be achieved in a number of ways. Major process inventions often involve the development of a new route, i.e. a new sequence of chemical steps from a raw material to the product. Alternatively they may involve the use of existing routes, but under radically changed conditions. Such inventions may produce cost benefits in terms of reduced raw material cost or reduced process complexity (e.g. number of steps, amount of separation, rigour of conditions, etc.). The implementation of major process inventions usually involves the construction of a new plant. Minor, incremental, inventions may lead to cost reduction through yield increase, increase in catalyst life, reduction in purification costs, etc. This type of invention usually does not require new plant construction. Clearly, as Schmookler indicated, the expected gain from inventive activity of this type varies with expected sales. However, just as clearly it also
3. Synthetic fibres The commercial history of synthetic fibres started in 1938 with the first full-scale production of nylon 66. Nylon 6 followed in 1940, acrylic fibres in 1950 and polyester in 1951. Polypropylene, which is substantially less important, came into use in 1967, and there are a number of other fibres made in relatively small tonnages. The development of output of the major fibres is shown in fig. 1. Nylon 6 and nylon 66 are virtually completely interchangeable in applications and can be assumed to be subject to identical market effects. Most statistics do not in fact distinguish between the two. All the major fibres may be expected to be affected by similar broad market trends, and it can be seen that the production data do exhibit similar variations. A striking feature of the development of the market is the very rapid growth of polyester production during the period 1965-1973.
P.
.... .. . .. .. .
W~semun
/
Patenting
and rnventiue
331
crctiui[>
I’
ACRYLIC
I I
NYLON
: I
_-----
I
POLYESTER
,
Fig. 1. World production
I970
1960
1950
1940
of major synthetic
1980
fibres. Source of data: Textile Organon.
of the major synthetic fibres. For eight of these, counts of patents on manufacturing processes were taken from Chemical Abstracts, the main abstract-
Synthetic fibres are made from petrochemical intermediates (fig. 2). There are ten intermediates that are used entirely or largely in the manufacture CYCLOHEXANE
CYCLOHEXANOL 6 CYCLOHEXANONE
P-XYLENE 100 I ADIPONITRILE
/
TEREPHTHALIC ACID
100
I
HEXAMETHYLENE
ETHYLENE
v 100
DlAb4l~~
GLYCOL 50
t
ACRYLICS
Fig. 2. Major synthetic indicated.
NYLON
NYLON
66
fibres and intermediates.
Numbers
POLYESTER
6
represent
approximate
percentages
of products
used in the applications
Fig. 3. Cyclohexane
process
patents
1950
1940
Fig
4.
Adipic
acid process
Fig. 5. Adiponitrile
process
patents.
patents.
I960
1970
1900
333
1940
1950
Fig. 6. Hexamethylenediamine
100
process
patents.
I
9080-
70-
20-
IO -
1940
Fig. 7. Caprolactam
1950
process
I960
1970
Iwo
patents.
ing work for chemical literature, and the resulting time series are shown in figs. 3-10. 1 The dates plotted are the dates at which the patents were abstracted. These lag the date of the invention
Patents for cyclohexanol and cyclohexanone were not counted since here the situation is confused by the fact that these products are often, but not always, produced in the same process.
because
of delays caused by the following:
(1) drawing up and entering the patent application; (2) examination and publication of the patent; (3) abstracting the patent. Of these, (1) is likely generally to be minimal, (2) varies widely, but is often about 3 years, and (3) is usually only a few months. Overall, the total lag is
1950
1940
Fig. 8. Acrylonitrile
process
patents.
probably often about 4 years from the time at which the invention was made. The research work is likely to have started anything from about 6 months before that. There are major differences between the time series. Three of the nylon intermediates, adipic acid, adiponitrile, and caprolactam, show broadly similar cyclic patterns of patenting activity. Activity on the other two, cyclohexane and hexamethylenediamine, has been much more even, and at a lower level. The contrast between adiponitrile and hexamethylenediamine, which have identical demand patterns, is particularly striking. The time
50
series for the patents on intermediates for acrylic and polyester fibres, acrylonitrile, p-xyiene, and terephthalic acid, differ markedly from the other five. Here inventive activity preceded the build up of demand, and has been at a relatively high level. It is evident that overall the series are not consistent with any simple demand-pull theory. The two intermediates for which patenting activity has been at a low level throughout their commercial life are both made by a process for which it is difficult to envisage substantial improvements. Cyclohexane is mainly made by hydrogenation of benzene. The process operates
-
1940
Fig. 9. p-Xylene
process
I950
patents.
1960
1970
1980
335
1940
Fig. 10. Terephthalic
1950
acid process
I960
patents
under simple, lowcost conditions, and gives virtually 100 percent yield. Commentators have stated that the pre-eminence of cyclohexane-based routes to nylon “is largely due to the simplicity of the method of producing cyclohexane on an industrial scale by the hydrogenation of benzene” [5]. Hexamethylenediamine is made by hydrogenation of adiponitrile. Again the process is simple, and gives very high yields [6]. The processes used for the other intermediates have all showed much greater scope for improvement. Two of these intermediates, which have been the subject of major process inventions, have been examined in detail. 3.1. Adiponitrile Until 1965, adiponitrile was mostly made by the reaction of adipic acid with ammonia. The main economic disadvantage of this process is that adipic acid is relatively expensive, so that major cost reduction required the development of a new route. It can be seen from fig. 5 that patenting activity on adiponitrile remained at a fairly low level until the mid 1960s (abstract date), and that there was a marked peak in activity around 1970. The patents
on adiponitrile were examined, and divided into categories (fig. 11). lnitially patenting activity on adiponitrile was on a variety of new routes and to a lesser extent on improvements on the adipic acid based route. In 1962 abstracts started to appear on patents covering, the production of adiponitrile by hydrodimerisation of acrylonitrile, and as can be seen, patents on this process accounted for most of the activity around 1970. A process based on this route was put into commercial operation by Monsanto in the U.S.A. in 1965, and the same company brought a plant into operation in the U.K. in 1978 [7]. Another process independently developed by Asahi is operated commercially [S], and a number of others have reached the pilot plant stage [9]. This type of process is now of substantial, though by no means overwhelming, commercial importance. Hydrodimerisation of acrylonitrile involves the reaction acrylonitrile
+ hydrogen
(free or combined)
-+ adiponitrile It has evident attractions as a route to adiponitrile in terms of raw material cost, and was in fact the subject of a patent in 1948 [lo]. However, the yield
I940 Fig. 11. Adiponitrile
1950 patents
by process
I960 type.
claimed was low and the conditions used were technologically inconvenient. In 1957 Russian chemists published a paper giving details of a method by which the reaction could be brought about easily and in good yield [ll]. M.M. Baizer, the chemist responsible for the invention of the Monsanto version of the process, has clearly indicated that this paper provided the stimulus for his work. Thus, “The immediate impetus for a re-examination of the possibilities for an acrylonitrile to adiponitrile process was a paper by Knunyants and Vyazankin which came to the attention of our vice-president (now retired) for research and development” [12]. The first Monsanto patent application was made in December 1960 and the patent was issued in May 1963 [13]. Baizer received the Chemical Engineering Kirkpatrick Award for his work on this process. Patents on hydrodimerisation of acrylonitrile were issued to a group of workers at the Weizmann Institute in Israel in 1961 and 1963 [14]. The method used was quite distinct from that used by Monsanto. The first patents issued to companies other than Monsanto were to Rhone-Poulenc [15], ICI [16], and du Pont [17]. The Rhone-Poulenc version of hydrodimerisation was also quite distinct from that used by Monsanto, whereas those
of ICI and du Pont had similarities with it. The timing of all these patents is consistent with the work leading to them having been stimulated by Knunyants and Vyazankin’s paper, though it is about not inconceivable that information Monsanto’s work may have been available to some of the inventors. Abstracts of patents by other companies began to appear in 1968, and the number of companies involved increased rapidly. By 1971 a total of 17 companies had taken out patents in this field. The late entrants, who may be assumed to be secondary, imitative, inventors, made up the bulk of the peak in activity around 1970. 3.2. Acrylonitrile Acrylonitrile was first used commercially in the 1930s in the manufacture of nitrile rubber. This use built up to a moderate scale during World War II. In 1950 when acrylic fibres were introduced there were two processes in commercial use, based on the reaction of hydrogen cyanide with acetylene and with ethylene oxide respectively. During the 1950s the process based on acetylene became predominant, since it had advantages in raw material costs and in only having one stage. Nonetheless, it was far from ideal as a chemical process since it
337
1940
1960
1950
Fig. 12. Acrylonitrile
patents
by process
type.
was based on relatively expensive raw materials, had only a moderate yield, and presented some operational difficulties in terms of loss of catalyst activity and purification problems. In 1960 a new process, the ammoxidation process, was introduced, and this had such marked economic advantage over the existing processes that it rapidly displaced them. By 1970 virtually all acrylonitrile was made by the ammoxidation process. The patents on acrylonitrile were classified by process type (fig. 12). It can be seen that the marked increase in activity during 1953-57, representing inventions made during approximately 1949-53, was centred largely on the acetylenebased process, which, as has been indicated, offered considerable scope for incremental improvement. This activity was probably a response to predictions of demand for acrylic fibres, and therefore for
Table 1 Ammoxidation
DCL” Sohio Others
and related
patents,
acrylonitrile, based on the sales record of the pioneering synthetic fibre nylon. Thus, in March 1952 Howard Bunn of Carbide and Carbon Corporation in the U.S.A. wrote “Acrylonitrile production, on the other hand, will need a large boost to meet demands for its use in Orlon, Dynel, Acrilan, and the projected fibres yet to come. All this new fibre production depends on provisions for new acrylonitrile capacity.” [18]. The ammoxidation process was invented independently by two companies, the Distillers Company Ltd. in the U.K., and Sohio in the U.S.A. The first patents relating to ammoxidation, by Distillers, were abstracted in 1955 [19], Sohio’s first patent was abstracted in 1960 [20], though it has been reported that the company had started work on the process in 1949 [21]. Sohio were first to commercialise the process, and have held a
by company
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1970
1975
1980
3 0 0
1 0 0
0 0 0
1 0 0
1 0 0
1 1 1
2 0 1
5 2 5
3 0 14
4 1 18
8 4 12
0 1 23
0 6 25
0 7 13
a DCL sold their petrochemical
interests
to British Petroleum
in 1967.
dominant position in the technology ever since. Patents by other companies began to appear in the abstracts in significant numbers by 1962, and from 1963 these secondary inventions made up the bulk of the activity (table 1). D.J. Hadley, one of the inventors of the Distillers Company version of the process, has given a clear indication that its invention arose out of a previously developed process for the oxidation of “In the early 1950’s the propylene to acrolein: Research Department of the Distillers Company Ltd. was studying the chemical reactions of acrolein, with the objective of finding new uses for this material, for they had recently developed a process for its production by the vapour phase oxidation of propylene . . . . A prime objective of the research on acrolein was acrylonitrile, which it was found could be prepared by the vapour phase reaction of acrolein with ammonia over dehydrogenation catalysts. . . subsequently a research programme was initiated with the object of finding an alternative catalyst for the one-stage conversion of propylene to acrylonitrile.” (i.e. for ammoxidation) [22]. There is evidence that the work on ammoxidation at Sohio was also stimulated in the same way [21]. Patenting activity on the ammoxidation process has remained at a relatively high level. This probably reflects a combination of two factors. First, the process initially had a yield of only about 56 percent, and the yield is probably still less than 80 percent. Secondly, this type of process offers extensive scope for inventions involving changes in catalyst composition.
4. Conclusions The time series of patents which considered fall into three groups:
(1) the nylon
have
These series are evidently not consistent with a simple demand-pull theory. Such a theory would not, for instance, account for the low level of activity on cyclohexane and hexamethylenediamine. At the same time, there are indications, notably in the cyclic patterns of activity on the nylon intermediates, that common, presumably market-related, factors have influenced inventive activity. In the cases of acrylonitrile, terephthalic acid and p-xylene it seems evident that in the early 1950s any demand-side effects were related to projections of demand made in the light of the established commercial success of nylon. The series are consistent with the view that perceived technological opportunity for process improvement is a major factor in determining level of inventive activity. This view is reinforced by analysis of the patents on adiponitrile and acrylonitrile, and this analysis also supports the view that developments in science and technology can, by introducing new opportunities, stimulate inventions. In the case of adiponitrile, after more than 20 years of relatively low activity, there was a major burst of patenting of hydrodimersation processes, starting about five years after the publication of a novel scientific paper on hydrodimerisation. The timing, together with the acknowledgement by one of the inventors of the key role of the paper in stimulating his work, leaves little doubt that this was a case of science-push. Similarly, there is good evidence that the invention of the ammoxidation process for the production of acrylonitrile was stimulated by the prior invention of a process for making acrolein, i.e. that it represents a case of technology-push. In both the above cases, the initial invention rapidly stimulated a large number of secondary, imitative inventions.
been
intermediates adipic acid, adiponitrile and caprolactam, with broadly similar cyclic patterns of activity; cyclohexane and (2) the nylon intermediates hexamethylenediamine, with much lower and more even levels of activity; for acrylic and polyester (3) the intermediates acrylonitrile, terephthalic acid and fibres, p-xylene, with major inventive activity preceding the build up of demand.
References [l] D. Mowery and N. Rosenberg, The Influence of Market Demand upon Innovation: a Critical Review of Some Recent Empirical Studies, Research Policy 8 (1979) 102-153. [2] V.M. Walsh, J.F. Townsend, B.G. Achilladelis and C. Freeman, Trends in Imention and Innovation in the Chemical Industy, Science Policy Research Unit, University of Sussex, Report to SSRC (June 1979). [3] J. Schmookler, Invention and Economic Growth (Harvard University Press, Cambridge, MA, 1966).
P. Wisemun / Patenting und incwaioe uctiui
[4] C. Freeman, The Determinants of Innovation: Market Demand, Technology, and the Response to Social Problems, Fuiures 11 (1979) 206-215. [5] E.G. Hancock, Benzene and its Industrial Derivatives (Berm, London, 1975) p. 219. [6] F.A. Lowenheim and M.K. Moran, Faith, Keyes and Clark’s Industrral Chemicals, 4th edn. (John Wiley, New York, 1975) p. 442. [7] D.E. Danly, Discovery, Development and Commercialisation of the Electrochemical Adiponitrile Process, Part II, Chemistry and Industry (1979) 439-447. [8] Kirk-Othmer Encyclopnedia of Chemical Technology 3rd edn., Vol. 8 (John Wiley, New York, 1979) p. 707. [9] European Chemical News, April 17 (1970) 47; April 24 (1970) 42; May 1 (1970) 32. [lo] R.M. Leekley. US Patent 2 439 308, to du Pant, April 6, 1948. [ll] IL. Knunyants and N.S. Vyanzankin. Hydrodimerisation of Acrylonitrile. Izuestl_yu Akudemri Nuuk SSSR, Otdelenie Khimlcheshqu (1957) 238-240. [12] M.M. Baizer, Discovery, Development and Commercialisation of the Electrochemical Adiponitrile Process, Part I. Chemlsty and Industry (1979) 435-439. [13] M.M. Baizer. French Patent 1 328 327, to Monsanto, May 31, 1963, US application December 12. 1960 and October 16, 1961.
339
[14] A. Katchalsky, D. Vofsi and J.I. Padova. Israeli Patents 13 842, September 22. 1961 and 13 844. September 22, 1961, and British Patent 923 250, April 10, 1963, Israeli application May 8, 1960. 1151 P. Chabardes, C. Grard and M. Thiers. French Patent 1 377 425 to Rhone-Poulenc, November 6, 1964, application September 17. 1963. [16] ICI Ltd. French Patent 1 385 906, January 15, 1965. British application March 8, 1963 and Feburary 25. 1964. [17] W.J. Sloan and D.D. Davis, Belgian Patent 649 625, to du Pant, October 16, 1964. US application June 24, 25, 1963. [18] H. Bunn, Cost and Availability of Raw Materials, Indurtrrul crud Engitwenng Chemistry 44 (1952) 2128-2133. [19] F.J. Bellinger, T. Bewley and H.M. Stanley, British Patent 709 337. to Distillers Co. Ltd., May 19, 1954. F.J. Bellinger, T. Bewley and H.M. Stanley. US Patent 2 691 037, to Distillers Co. Ltd., October 5. 1954. B.K. Howe and T. Bewley, British Patent 719 635 to Distillers Co. Ltd., December 8. 1954. [20] J.D. Idol., Jr., US Patent 2 904 580, to Sohio. September 15. 1959. [21] B. Achilladelis, Process Innooution tn the Chemical Industrv, PhD Thesis (University of Sussex, 1973) p. 136. [22] D.J. Hadley, in: E.G. Hancock (ed.) Prop.b,lene und Its Indcutrirrl Deriuutrues (Benn, London, 1973) p, 420.
Patenting and inventive activity on synthetic fibre intermediates P. WISEMAN Departmentof Chemistry, UMIST,
Sackville Street, Manchester
Mb0 IQD,
U.K.
Final version received April 1983
The demand-pull theory of invention and innovation has drawn much of its support from the work of Jacob Schmookler on patent time series. In this work, Schmookler found no evidence that scientific discoveries or major inventions had provided the stimulus for important inventions. However, it is argued here that his method was not well designed to detect such effects. Any effect of a particular scientific or technological development is likely to occur in a rather narrow area of technology, so that detection of science-push and technology-push will be favoured by the examination of narrow areas of inventive activity. Manufacturing processes for groups of chemical products subject to similar demand-side factors provide convenient such areas. In this study time series of patents on processes for eight intermediates for synthetic fibres have been examined. They are not consistent with a simple demand-pull theory, but rather with the view that inventive activity is affected both by demand and by technological opportunity. Two of the intermediates have been examined in detail, and evidence has been presented that in one case a major invention arose from science-push and in the other one arose from technology-push.
1. Introduction The demand-pull theory of invention and innovation which ‘received much support during the late 1960s and early 1970s has recently been extensively criticised. For example, Mowery and Rosenberg argue that much of the evidence cited in support of the theory is inconclusive [l]. Walsh et al. have also pointed to weaknesses in arguments for the demand-pull theory [2]. They noted the influential role that Schmookler has had in this field, and while acknowledging the quality of his work, suggest that it is a less compelling demonstration of the primacy of market demand in determing inventive activity than has been suggested Research Policy 12 (1983) 329-339 North-Holland 0048-7333/83/$3.00
0 1983, Elsevier Science Publishers
by Schmookler and a number of later commentators. Schmookler drew up time series of patents on inventions in four industries - agriculture, paper making, petroleum refining, and railroads - and compared them with series for investment and/or output in these industries [3]. He found that for each of these industries there were great similarities in both long term trends and long term swings between the patent and economic time series, and concluded that “(1) invention is largely an economic activity which, like other economic activities, is pursued for gain; (2) expected gain varies with expected sales of goods embodying the invention; and (3) expected sales of goods are largely determined by present capital goods sales”. Further, on the basis of examination of the historical records of major inventions he stated “Despite the popularity of the idea that scientific discoveries and major inventions typically provide the stimulus for inventions, the historical record of important inventions in petroleum refining, paper making, railroading and farming revealed not a single unambiguous instance in which either discoveries or inventions played the role hypothesized”. Walsh et al. used techniques similar to those of Schmookler to examine inventive activity in a number of sections of the chemical industry. Freeman concluded with respect to this work that their results sometimes appeared “to validate Schmookler’s results, whilst in others a counterSchmookler pattern is discernible, and in still others no clear pattern emerges” [4]. Schmookler’s approach was not in fact well designed to detect science-push effects. His patent statistics covered all inventions in the industries concerned, and the nature of the technology involved was consequently very diverse. This can clearly be seen from his appendices listing im-
B.V. (North-Holland)
portant inventions in the industries. Science-push effects in the main would be expected to arise from rather specific discoveries in a particular science, and to affect a specific sector of the technology in the industry. For example, discoveries in a particular area of chemistry might be expected to have an effect on a particular chemical refinery process, but not on other chemical processes or on all the other areas of refinery technology, such as distiIlation and solvent extraction, which do not depend on chemical phenomena. In highly aggregated data such as that used by Schmookler, changes in inventive activity on specific areas of technology will tend to be lost in the overall noise. , Effects of supply-side technical factors on inventive activity are most likely to be evident when narrow technological regions are examined. Walsh et al. examined much narrower areas than Schmookler, but a number were still broad enough to cause a substantial loss of definition in terms of effects. In this present work an attempt has been made to examine inventive activity in the chemical industry in areas narrow enough that specific effects on levels of activity can be observed. The areas chosen are concerned with process invention on selected products. 2. Process
depends on the technological opportunities for developing new or improved processes with reduced costs. The extent of these opportunities is determined (i) by the technological state of existing processes, and (ii) by the state of the relevant scientific and technological art. As the state of the art changes the extent of the opportunities may change. It is not unreasonable to expect that occasionally the changes will be such that important new opportunities suddenly become evident and major inventions will be initiated. ‘There are two major problems in trying to assess the extent to which inventive activity in the chemical industry is determined by economic or technical factors. One is that the commercial history of many of the major chemicals is relatively short, so that the identification and comparison of trends and patterns is difficult. The second is that economic data on chemical products are notoriously sparse. The approach that has been adopted here is to examine products subject to similar market factors on the supposition that ~~~~e~e~ce~ in inventive activity are likely to be due to causes other than demand-side factors. There are a number of pairs or groups of products subject to similar or identical market forces; intermediates for the manufacture of synthetic fibres form a particularly convenient group.
research and invention
The main objective of research on chemical processes is usually cost reduction. This may be achieved in a number of ways. Major process inventions often involve the development of a new route, i.e. a new sequence of chemical steps from a raw material to the product. Alternatively they may involve the use of existing routes, but under radically changed conditions. Such inventions may produce cost benefits in terms of reduced raw material cost or reduced process complexity (e.g. number of steps, amount of separation, rigour of conditions, etc.). The implementation of major process inventions usually involves the construction of a new plant. Minor, incremental, inventions may lead to cost reduction through yield increase, increase in catalyst life, reduction in purification costs, etc. This type of invention usually does not require new plant construction. Clearly, as Schmookler indicated, the expected gain from inventive activity of this type varies with expected sales. However, just as clearly it also
3. Synthetic fibres The commercial history of synthetic fibres started in 1938 with the first full-scale production of nylon 66. Nylon 6 followed in 1940, acrylic fibres in 1950 and polyester in 1951. Polypropylene, which is substantially less important, came into use in 1967, and there are a number of other fibres made in relatively small tonnages. The development of output of the major fibres is shown in fig. 1. Nylon 6 and nylon 66 are virtually completely interchangeable in applications and can be assumed to be subject to identical market effects. Most statistics do not in fact distinguish between the two. All the major fibres may be expected to be affected by similar broad market trends, and it can be seen that the production data do exhibit similar variations. A striking feature of the development of the market is the very rapid growth of polyester production during the period 1965-1973.
P.
.... .. . .. .. .
W~semun
/
Patenting
and rnventiue
331
crctiui[>
I’
ACRYLIC
I I
NYLON
: I
_-----
I
POLYESTER
,
Fig. 1. World production
I970
1960
1950
1940
of major synthetic
1980
fibres. Source of data: Textile Organon.
of the major synthetic fibres. For eight of these, counts of patents on manufacturing processes were taken from Chemical Abstracts, the main abstract-
Synthetic fibres are made from petrochemical intermediates (fig. 2). There are ten intermediates that are used entirely or largely in the manufacture CYCLOHEXANE
CYCLOHEXANOL 6 CYCLOHEXANONE
P-XYLENE 100 I ADIPONITRILE
/
TEREPHTHALIC ACID
100
I
HEXAMETHYLENE
ETHYLENE
v 100
DlAb4l~~
GLYCOL 50
t
ACRYLICS
Fig. 2. Major synthetic indicated.
NYLON
NYLON
66
fibres and intermediates.
Numbers
POLYESTER
6
represent
approximate
percentages
of products
used in the applications
Fig. 3. Cyclohexane
process
patents
1950
1940
Fig
4.
Adipic
acid process
Fig. 5. Adiponitrile
process
patents.
patents.
I960
1970
1900
333
1940
1950
Fig. 6. Hexamethylenediamine
100
process
patents.
I
9080-
70-
20-
IO -
1940
Fig. 7. Caprolactam
1950
process
I960
1970
Iwo
patents.
ing work for chemical literature, and the resulting time series are shown in figs. 3-10. 1 The dates plotted are the dates at which the patents were abstracted. These lag the date of the invention
Patents for cyclohexanol and cyclohexanone were not counted since here the situation is confused by the fact that these products are often, but not always, produced in the same process.
because
of delays caused by the following:
(1) drawing up and entering the patent application; (2) examination and publication of the patent; (3) abstracting the patent. Of these, (1) is likely generally to be minimal, (2) varies widely, but is often about 3 years, and (3) is usually only a few months. Overall, the total lag is
1950
1940
Fig. 8. Acrylonitrile
process
patents.
probably often about 4 years from the time at which the invention was made. The research work is likely to have started anything from about 6 months before that. There are major differences between the time series. Three of the nylon intermediates, adipic acid, adiponitrile, and caprolactam, show broadly similar cyclic patterns of patenting activity. Activity on the other two, cyclohexane and hexamethylenediamine, has been much more even, and at a lower level. The contrast between adiponitrile and hexamethylenediamine, which have identical demand patterns, is particularly striking. The time
50
series for the patents on intermediates for acrylic and polyester fibres, acrylonitrile, p-xyiene, and terephthalic acid, differ markedly from the other five. Here inventive activity preceded the build up of demand, and has been at a relatively high level. It is evident that overall the series are not consistent with any simple demand-pull theory. The two intermediates for which patenting activity has been at a low level throughout their commercial life are both made by a process for which it is difficult to envisage substantial improvements. Cyclohexane is mainly made by hydrogenation of benzene. The process operates
-
1940
Fig. 9. p-Xylene
process
I950
patents.
1960
1970
1980
335
1940
Fig. 10. Terephthalic
1950
acid process
I960
patents
under simple, lowcost conditions, and gives virtually 100 percent yield. Commentators have stated that the pre-eminence of cyclohexane-based routes to nylon “is largely due to the simplicity of the method of producing cyclohexane on an industrial scale by the hydrogenation of benzene” [5]. Hexamethylenediamine is made by hydrogenation of adiponitrile. Again the process is simple, and gives very high yields [6]. The processes used for the other intermediates have all showed much greater scope for improvement. Two of these intermediates, which have been the subject of major process inventions, have been examined in detail. 3.1. Adiponitrile Until 1965, adiponitrile was mostly made by the reaction of adipic acid with ammonia. The main economic disadvantage of this process is that adipic acid is relatively expensive, so that major cost reduction required the development of a new route. It can be seen from fig. 5 that patenting activity on adiponitrile remained at a fairly low level until the mid 1960s (abstract date), and that there was a marked peak in activity around 1970. The patents
on adiponitrile were examined, and divided into categories (fig. 11). lnitially patenting activity on adiponitrile was on a variety of new routes and to a lesser extent on improvements on the adipic acid based route. In 1962 abstracts started to appear on patents covering, the production of adiponitrile by hydrodimerisation of acrylonitrile, and as can be seen, patents on this process accounted for most of the activity around 1970. A process based on this route was put into commercial operation by Monsanto in the U.S.A. in 1965, and the same company brought a plant into operation in the U.K. in 1978 [7]. Another process independently developed by Asahi is operated commercially [S], and a number of others have reached the pilot plant stage [9]. This type of process is now of substantial, though by no means overwhelming, commercial importance. Hydrodimerisation of acrylonitrile involves the reaction acrylonitrile
+ hydrogen
(free or combined)
-+ adiponitrile It has evident attractions as a route to adiponitrile in terms of raw material cost, and was in fact the subject of a patent in 1948 [lo]. However, the yield
I940 Fig. 11. Adiponitrile
1950 patents
by process
I960 type.
claimed was low and the conditions used were technologically inconvenient. In 1957 Russian chemists published a paper giving details of a method by which the reaction could be brought about easily and in good yield [ll]. M.M. Baizer, the chemist responsible for the invention of the Monsanto version of the process, has clearly indicated that this paper provided the stimulus for his work. Thus, “The immediate impetus for a re-examination of the possibilities for an acrylonitrile to adiponitrile process was a paper by Knunyants and Vyazankin which came to the attention of our vice-president (now retired) for research and development” [12]. The first Monsanto patent application was made in December 1960 and the patent was issued in May 1963 [13]. Baizer received the Chemical Engineering Kirkpatrick Award for his work on this process. Patents on hydrodimerisation of acrylonitrile were issued to a group of workers at the Weizmann Institute in Israel in 1961 and 1963 [14]. The method used was quite distinct from that used by Monsanto. The first patents issued to companies other than Monsanto were to Rhone-Poulenc [15], ICI [16], and du Pont [17]. The Rhone-Poulenc version of hydrodimerisation was also quite distinct from that used by Monsanto, whereas those
of ICI and du Pont had similarities with it. The timing of all these patents is consistent with the work leading to them having been stimulated by Knunyants and Vyazankin’s paper, though it is about not inconceivable that information Monsanto’s work may have been available to some of the inventors. Abstracts of patents by other companies began to appear in 1968, and the number of companies involved increased rapidly. By 1971 a total of 17 companies had taken out patents in this field. The late entrants, who may be assumed to be secondary, imitative, inventors, made up the bulk of the peak in activity around 1970. 3.2. Acrylonitrile Acrylonitrile was first used commercially in the 1930s in the manufacture of nitrile rubber. This use built up to a moderate scale during World War II. In 1950 when acrylic fibres were introduced there were two processes in commercial use, based on the reaction of hydrogen cyanide with acetylene and with ethylene oxide respectively. During the 1950s the process based on acetylene became predominant, since it had advantages in raw material costs and in only having one stage. Nonetheless, it was far from ideal as a chemical process since it
337
1940
1960
1950
Fig. 12. Acrylonitrile
patents
by process
type.
was based on relatively expensive raw materials, had only a moderate yield, and presented some operational difficulties in terms of loss of catalyst activity and purification problems. In 1960 a new process, the ammoxidation process, was introduced, and this had such marked economic advantage over the existing processes that it rapidly displaced them. By 1970 virtually all acrylonitrile was made by the ammoxidation process. The patents on acrylonitrile were classified by process type (fig. 12). It can be seen that the marked increase in activity during 1953-57, representing inventions made during approximately 1949-53, was centred largely on the acetylenebased process, which, as has been indicated, offered considerable scope for incremental improvement. This activity was probably a response to predictions of demand for acrylic fibres, and therefore for
Table 1 Ammoxidation
DCL” Sohio Others
and related
patents,
acrylonitrile, based on the sales record of the pioneering synthetic fibre nylon. Thus, in March 1952 Howard Bunn of Carbide and Carbon Corporation in the U.S.A. wrote “Acrylonitrile production, on the other hand, will need a large boost to meet demands for its use in Orlon, Dynel, Acrilan, and the projected fibres yet to come. All this new fibre production depends on provisions for new acrylonitrile capacity.” [18]. The ammoxidation process was invented independently by two companies, the Distillers Company Ltd. in the U.K., and Sohio in the U.S.A. The first patents relating to ammoxidation, by Distillers, were abstracted in 1955 [19], Sohio’s first patent was abstracted in 1960 [20], though it has been reported that the company had started work on the process in 1949 [21]. Sohio were first to commercialise the process, and have held a
by company
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1970
1975
1980
3 0 0
1 0 0
0 0 0
1 0 0
1 0 0
1 1 1
2 0 1
5 2 5
3 0 14
4 1 18
8 4 12
0 1 23
0 6 25
0 7 13
a DCL sold their petrochemical
interests
to British Petroleum
in 1967.
dominant position in the technology ever since. Patents by other companies began to appear in the abstracts in significant numbers by 1962, and from 1963 these secondary inventions made up the bulk of the activity (table 1). D.J. Hadley, one of the inventors of the Distillers Company version of the process, has given a clear indication that its invention arose out of a previously developed process for the oxidation of “In the early 1950’s the propylene to acrolein: Research Department of the Distillers Company Ltd. was studying the chemical reactions of acrolein, with the objective of finding new uses for this material, for they had recently developed a process for its production by the vapour phase oxidation of propylene . . . . A prime objective of the research on acrolein was acrylonitrile, which it was found could be prepared by the vapour phase reaction of acrolein with ammonia over dehydrogenation catalysts. . . subsequently a research programme was initiated with the object of finding an alternative catalyst for the one-stage conversion of propylene to acrylonitrile.” (i.e. for ammoxidation) [22]. There is evidence that the work on ammoxidation at Sohio was also stimulated in the same way [21]. Patenting activity on the ammoxidation process has remained at a relatively high level. This probably reflects a combination of two factors. First, the process initially had a yield of only about 56 percent, and the yield is probably still less than 80 percent. Secondly, this type of process offers extensive scope for inventions involving changes in catalyst composition.
4. Conclusions The time series of patents which considered fall into three groups:
(1) the nylon
have
These series are evidently not consistent with a simple demand-pull theory. Such a theory would not, for instance, account for the low level of activity on cyclohexane and hexamethylenediamine. At the same time, there are indications, notably in the cyclic patterns of activity on the nylon intermediates, that common, presumably market-related, factors have influenced inventive activity. In the cases of acrylonitrile, terephthalic acid and p-xylene it seems evident that in the early 1950s any demand-side effects were related to projections of demand made in the light of the established commercial success of nylon. The series are consistent with the view that perceived technological opportunity for process improvement is a major factor in determining level of inventive activity. This view is reinforced by analysis of the patents on adiponitrile and acrylonitrile, and this analysis also supports the view that developments in science and technology can, by introducing new opportunities, stimulate inventions. In the case of adiponitrile, after more than 20 years of relatively low activity, there was a major burst of patenting of hydrodimersation processes, starting about five years after the publication of a novel scientific paper on hydrodimerisation. The timing, together with the acknowledgement by one of the inventors of the key role of the paper in stimulating his work, leaves little doubt that this was a case of science-push. Similarly, there is good evidence that the invention of the ammoxidation process for the production of acrylonitrile was stimulated by the prior invention of a process for making acrolein, i.e. that it represents a case of technology-push. In both the above cases, the initial invention rapidly stimulated a large number of secondary, imitative inventions.
been
intermediates adipic acid, adiponitrile and caprolactam, with broadly similar cyclic patterns of activity; cyclohexane and (2) the nylon intermediates hexamethylenediamine, with much lower and more even levels of activity; for acrylic and polyester (3) the intermediates acrylonitrile, terephthalic acid and fibres, p-xylene, with major inventive activity preceding the build up of demand.
References [l] D. Mowery and N. Rosenberg, The Influence of Market Demand upon Innovation: a Critical Review of Some Recent Empirical Studies, Research Policy 8 (1979) 102-153. [2] V.M. Walsh, J.F. Townsend, B.G. Achilladelis and C. Freeman, Trends in Imention and Innovation in the Chemical Industy, Science Policy Research Unit, University of Sussex, Report to SSRC (June 1979). [3] J. Schmookler, Invention and Economic Growth (Harvard University Press, Cambridge, MA, 1966).
P. Wisemun / Patenting und incwaioe uctiui
[4] C. Freeman, The Determinants of Innovation: Market Demand, Technology, and the Response to Social Problems, Fuiures 11 (1979) 206-215. [5] E.G. Hancock, Benzene and its Industrial Derivatives (Berm, London, 1975) p. 219. [6] F.A. Lowenheim and M.K. Moran, Faith, Keyes and Clark’s Industrral Chemicals, 4th edn. (John Wiley, New York, 1975) p. 442. [7] D.E. Danly, Discovery, Development and Commercialisation of the Electrochemical Adiponitrile Process, Part II, Chemistry and Industry (1979) 439-447. [8] Kirk-Othmer Encyclopnedia of Chemical Technology 3rd edn., Vol. 8 (John Wiley, New York, 1979) p. 707. [9] European Chemical News, April 17 (1970) 47; April 24 (1970) 42; May 1 (1970) 32. [lo] R.M. Leekley. US Patent 2 439 308, to du Pant, April 6, 1948. [ll] IL. Knunyants and N.S. Vyanzankin. Hydrodimerisation of Acrylonitrile. Izuestl_yu Akudemri Nuuk SSSR, Otdelenie Khimlcheshqu (1957) 238-240. [12] M.M. Baizer, Discovery, Development and Commercialisation of the Electrochemical Adiponitrile Process, Part I. Chemlsty and Industry (1979) 435-439. [13] M.M. Baizer. French Patent 1 328 327, to Monsanto, May 31, 1963, US application December 12. 1960 and October 16, 1961.
339
[14] A. Katchalsky, D. Vofsi and J.I. Padova. Israeli Patents 13 842, September 22. 1961 and 13 844. September 22, 1961, and British Patent 923 250, April 10, 1963, Israeli application May 8, 1960. 1151 P. Chabardes, C. Grard and M. Thiers. French Patent 1 377 425 to Rhone-Poulenc, November 6, 1964, application September 17. 1963. [16] ICI Ltd. French Patent 1 385 906, January 15, 1965. British application March 8, 1963 and Feburary 25. 1964. [17] W.J. Sloan and D.D. Davis, Belgian Patent 649 625, to du Pant, October 16, 1964. US application June 24, 25, 1963. [18] H. Bunn, Cost and Availability of Raw Materials, Indurtrrul crud Engitwenng Chemistry 44 (1952) 2128-2133. [19] F.J. Bellinger, T. Bewley and H.M. Stanley, British Patent 709 337. to Distillers Co. Ltd., May 19, 1954. F.J. Bellinger, T. Bewley and H.M. Stanley. US Patent 2 691 037, to Distillers Co. Ltd., October 5. 1954. B.K. Howe and T. Bewley, British Patent 719 635 to Distillers Co. Ltd., December 8. 1954. [20] J.D. Idol., Jr., US Patent 2 904 580, to Sohio. September 15. 1959. [21] B. Achilladelis, Process Innooution tn the Chemical Industrv, PhD Thesis (University of Sussex, 1973) p. 136. [22] D.J. Hadley, in: E.G. Hancock (ed.) Prop.b,lene und Its Indcutrirrl Deriuutrues (Benn, London, 1973) p, 420.