GB2250992A

GB2250992A - Tetrazole blowing agents

Info

Publication number: GB2250992A
Application number: GB9124976A
Authority: GB
Inventors: Atsuhiro Onishi; Koichi Matsunami; Masanao Ebara; Hiroaki Tanaka
Original assignee: Toyo Kasei Kogyo Co Ltd
Current assignee: Toyo Kasei Kogyo Co Ltd
Priority date: 1990-11-26
Filing date: 1991-11-25
Publication date: 1992-06-24
Anticipated expiration: 2011-11-25
Also published as: FR2669641B1; DE4138182A1; GB2250992B; FR2669641A1; GB9124976D0

Abstract

The blowing agents comprise tetrazoles and their derivatives which have melting points over 200 DEG C and are used to manufacture high quality foaming thermoplastic synthetic resin moldings, especially engineering or superengineering plastics moldings. The tetrazoles are of formulae (I) to (V) where the definitions are to be formed inside the specification. <IMAGE>

Description

22309?2 TETRAZOLE BLOWING AGENTS The present invention relates to

tetrazole blowing agents which are used in the manufacture of foamed thermoplastic resins.

Blowing agents formerly used in the manufacture of foamed thermoplastic synthetic resins include volatile hydrocarbons such as propane, butane, pentane and heptane and compounds which decompose at low temperatures, such as diazo-compounds, and these blowing agents have been used in a fixed molding process.

Blowing agents whi0h have previously been used for ordinary foamed synthetic resin plastics moldings have low vaporization temperatures and/or low thermal decomposition temperatures. Therefore, synthetic resins which may be used with these blowing agents have been limited to ordinary synthetic resins which have low melting points. Recently, the demand for thprmoplastic engineering plastics moldings has ingreased: 'Also, since the development of thermo- plastic superengineering plastics moldings containing liquid crystals, the demand for high quality cell structured artificial plastics is also on the incriase. In general, however, ordinary blowing agents are not used for engineering plastics moldings or superengineering plastics moldings which have high melting points or high softening points compared with ordinary thermoplastic moldings. Therefore, high quality foamed resins have not been manufactured using said ordinary blowing agents.

The object of the present invention is to provide blowing agents which have the following properties (a) - (c) such that they may be used in the manufacture of high quality thermoplastic synthetic resin moldings:

(a) a thermal decomposition temperature of at - 2 (b) (c) least 20CC; an ability to generate a large quantity of gas (non-toxics) on decomposition; an ability to generate decomposition gases which do not cause deterioration or degradation of the thermoplastic synthetic resin, such as ammonia or alcohol.

To attain the above described object, the inventors of the present invention have found that the tetrazoles described below and their derivatives satisfy the above properties (a) - (c). As a result of their investigations, the inventors have discovered that by using these tetrazoles and their derivatives as blowing agents, the manufacture of cell structured artificial plastics which have no shrink and warp has proved possible. Accordingly, the present invention provides single or plural tetrazoles and their de-rivatives which have the following structural formulae which are useful in the manufacture of foamed thermoplastic synthetic resins. The structural formulae used for the foamed thermoplastic synthetic resins are as follows:

R2 R2 N - N N - N N = C = N 11 11 11 l N C w \1 N R N C N R (1) N = C -"' N = (2) C N N N NI N N (4) N = C C = N - M - N NI = N (6) N N =, N R1 N = N N - M - N (3) N C - R2 N M z (5) N = M - 4 (a) wherein in compounds (1) and (2):

R. and Rl are the same or different and may be selected from H, Cl - C6 alkyl, cycloalkyl or alkenyl and these radicals can have side chains and also these radicals can be substituted by -COOH, -S03H, -N02, halogen, and -NR05 wherein R4 and R5 may each be H or Cl - C3 alkyl or R, Rl can be a phenyl, benzyl or phenethyl radical optionally substituted by 1 to 3 substituents selected from halogen, -N02, -CN, -COOH, -NR05, wherein R4 and R5 are as defined above, Cl - C4 alkyl, or can be substituted by the esters or amides of the lower fatty acids.

(b) in compounds (3), (4), (5) and (6):

R2 is H, -OH, -COOH, S03H, -N02, halogen, -NR4RS wherein R4 and R5 are as described 1 above, or Cl - C6 alkyl, alkylene, cycloalkyl, cycloalkylene, alkenyl or alkenylene radical and these radicals can also contain side chain, and alkyl, alkylene, cycloalkyl, cycloalkylene, alkenyl or alkenylene radical and these radicals can also contain side chain. And, alkyl, alkylene, cycloalkyl, cycloalkylene, alkenyl or alkenylene radicals can also be substituted by -OH, -COOH, -S03H, -N02, halogen and -NR05 wherein R4 and R5 are as described above, or also can be substituted through R2 same or the different tetrazoles or tetrazole metal salts. And, alkylene and alkenylene radicals can contain -0-, -N-, -S-, S02 or COradicals within the carbon chain of the molecules or can be substituted 1 - 2 numbers of phenyl radicals, and also contain phenylene or bisphenylene radicals within the 1 carbon chain of the alkylene or alkenylene radicals, and moreover these phenylene or bisphenylene radicals can be substituted 1 - 8 numbers of halogen, -OH, -N02, -NR05 wherein R4 and RS are as described above, or the esters-of lower carboxylic acids or their amides, and also phenylene or bisphenylene radicals can be substituted 1 - 8 numbers of Cl - C4 alkyl radicals. And, at the same time it is preferable that R2 is phenyl, benzyl, or phenethyl radicals, and it is preferable that said radicals above described are substituted by 1 - 3 halogen, -OH, -N02, -NROS wherein R4 and R5 are as described above, or the esters of lower carboxylic acids or their amides. And phenyl, phenylene or benzyl radicals can be substituted by 1 - 3 Cl - C4 alkyl radicals. m is a divalent metal selected from Ca, Cu, Zn, Mn, Fe, Co, Ni and Ba. Z is a univalent or divalent radical e.g., -S04. -NH4r -HC03r -HP04. -N03r ONH4r -CH3r -C2H5r -CHO, -NH2 or -S03H which form salts by combining with divalent metals.

The single or plural compounds selected from the above tetrazole derivatives have higher melting points or softening points than the thermoplastic synthetic resins used. The tetrazole derivative will typically be added in an amount of from 0.01 - 15 weight % per 100 weight % of the thermoplastic synthetic resins. In cases where the amount of blowing agent used is less than 0.001 weight %, the degree of foaming of the thermoplastic synthetic resins is inferior, and in the case where the amount of blowing agent used is over 15%, this is too great - 6 and the properties of the manufactured foamed synthetic resin molding products are inferior, and so both cases cannot be used in the present invention. As described above, the blowing agents of the present invention have higher thermal decomposition temperatures than the melting points or the softening points of the thermoplastic synthetic resins used, and, furthermore, the thermal decomposition points of the blowing agents are very-sensitive to the thermal decomposition at the higher molding temperature than the temperature of melting points or softening points of the thermoplastic synthetic resins. A fixed quantity of blowing agent is added to a master batch (polymer premixed with concentrated blowing agent) of thermoplastic resins treated previously to make chips or pellets which are mutually soluble and thus treated thermoplastic synthetic resins are used in molding. Typically, a blowing agent is premixed with an amount of, a first polymeric material and the premix is formed into chips or pellets and a fixed quantity of the premix is then added to a master batch of a second polymeric material to form a substantially homogeneous mixture which is then moulded. In the case where the first polymeric material and the second polymeric material are not the same, they are preferably mutually soluble in order to facilitate the formation of a substantially uniform structure in the product.

The thermoplastic synthetic resins that may be used in the present invention are not especially limited, but examples of thermoplastic resins which can be used include polyolefins, fluoropolymers, acrylonitrile butadiene - styrene resins, polystyrene, polyvinyl chloride (PVC) polyacrylates, polyamide, polycarbonate (PC), polyphenylene oxides (PPO), polyethylene terephthalates (PET), polybutylene 7 terephthalates (PBT), polyphenylene sulphides (PPS), polyether sulfone (PES), polyimide amide (PIA), polyether imide (PEI), polyether ether ketone (PEEK), polysulfonates (PSF), liquid crystal polymers (LCP), polytetrafluoroethylene (PTFE) or their compolymers or polyaromers.

Additionally, additives such as antioxidants, ultraviolet light absorption reagents, dyes, pigments, fillers or reinforcing fibers, etc. can be blended with the thermoplastic resins. In order to manufacture thermoplastic synthetic resi mouldings,injection molding, extrusion molding, blowing molding, press molding or any other type of molding technique can be used.

For instance, in injection molding the amount of blowing agent used is selected according to the desired properties of the molded product. The blowing agent is mixed with the thermoplastic synthetic resin a4d the mixture is injection molded in a conventional manner. In extrusion molding using a 2 axis extrusion molding machine, the desired thermoplastic synthetic resin is introduced into the hopper followed by a premix of blowing agent and a thermoplastic synthetic resin and then extruded in the usual way.

In order to reduce or prevent shrink and warp in the final product, full shot methods or slightly shot methods of molding are preferable. It is also preferable that the metal mold is maintained under a slightly reduced pressure or slightly short shot to obtain comparatively higher foaming rates. Moreover, in the case of the injection molding method, by using co-injection molding, from the same or different types of thermoplastic synthetic resin mixed with the blowing agents of the present invention, different kinds of thermoplastic synthetic resin can be - 8 manufactured where the non-foamed thermoplastic synthetic resins are present in greater amounts at the surface and the thermoplastic synthetic resins having foams with a high ratio are present at the interior of the product. Moldings with improved shrink and warp properties produced by injection molding are especially valuable in applications requiring surface smoothness and dimensional accuracy. And moreover, by using an extruder, various different types of extrusion moldings ca.n be manufactured by conventional methods e.g., fibers,' films or sheets or other various different types of extrusion foamed moldings using the thermoplastic synthetic resins including the blowing agents of the present invention.

By using the blowing agents of the present invention in the production of products having both foamed thermoplastic synthetic resin portions together with the non-foamed thermoplastic synthetic resin portions, con3ugate fibers or co-extruded fibers or sheets, extruded laminate fibers or sheets can be manufactured. Instead of the manufactured thermo plastic synthetic resin portion, paper, metals, ceramics or other materials can be used. These foamed moldings are characterised by light weight, adiabatic property, good cushioning property, beautiful appearance and shielding property of light and have various available uses.

The effects of the present invention may be summarised as follows:

(1) The provision of the blowing agents for use with high quality thermoplastic synthetic resins which have high melting points or high softening points is accomplished by the present invention. 35 (2) Thermal decomposition of the tetrazole 1 (3) 10:(4) (5) derivatives is complete and the main constituent of the decomposed gases is nitrogen and so has no harmful effects on the thermoplastic synthetic resin moldings, for instance, deterioration etc. of the moldings. It is possible by the present invention to provide thermoplastic engineering and superengineering plastics having a foamed structure which were formerly difficult to make. The foamed moldings of the present invention may be formed as fibers, films, sheets or 3dimensional moldings by using ordinary molding methods, e.g., extrusion, injection, blowing or press molding. In addition to the characteristics of the engineering and superengineering plastic moldings which themselves have high heat resistance and good mechanical properties, the foamed thermoplastic synthetic resin moldings which are manufactured by the present invention have the characteristics of light and beautiful surface appearance and no shrink and warp.

(EXAMPLE)

Example 1 (IH)-tetrazole (decomposition temperature 2410C) is added to the copolymerized nylon based on -NH(CH2)8CO- poly(9-amino nonanoic acid) 5 weight % and melted and the chips are made from them, and these chips are mixed with the 6 Nylon poly NH(CH2)3CO (melting point 215'C) 6.25, 8.0, 4.0 weight % each and then these are injection molded using test metal mold (length 60mm, breadth 40mm. and thickness 5mm) according to the conditions of Table 1 and the results are summarised. in Table 1.

the 12 Nvlon TABLE 1

Addition Injection Foaming Rate Quantity Specific Tempera- Molding Condition Gravity (Multiple) ture ( C) Tem. ( 0 C) No. 1 1.13 1.002 2 1.10 1.025 0.125.3 1.06 1.050 4 1.05 1.075 0.99 1.125 250 70 No. 1 1.12 1.005 2 1.07 1.050 0.25 3 1.05 1.075 4 0.95 1.125 0.94 1.175 No. 1 1.10 1.025 2 1.05 1.060 0.50 3 1.02 1.100 4 0.95 1.175 0.90 1.250 Wherein: Injection conditions are as follows:

No. 1 full shot No. 2 3.7% short shot No. 3 7.4% short shot No. 4 11.1% short shot No. 5 14.5% short shot - 12 Example 2..

Molding results by the full shot injection condition are summeLrized in Table 2.

TABLE 2

Blowing Decom- Kind of Molding Foaming Property of NO Agent posi- thermoTemp. Rate Molding foa- Addition tion plastic ( VC) (Multiple) ming form Quantity Temp. resins formability 0C (shrink,warp) Surface, (a) modified beautiful 1 0.125 283 PPE 290 1.002 no shrink no warp Surface, (b) beautiful 2 0.200 285 PC 300 1.004 no shrink, slightly warp Surface, (c) beautiful 3 0.125 276 PET 285 1.003 no shrink, no warp (d) _'- a I I I e e-. 4 4 0.200 276 PBT 280 1.003 above (e) 66 Same as 0.125 262 Nylon 275 1.002 above Wherein: Structural formula of the used tetrazoles in Table 2 (a) - (e) are as follows:

(a) N - N 11 11 C N CH3 / \ N / I Ph (d) N - N 1 11 c N H3CH2C N 1 -PN02ph 1.

(b) N N 11 11 c N H3CH2C N 1 en (e) N - N l l c N CH3 N 1 H (c) N - N 11 11 c N \/1, CH3 N A\ pN02Ph wherein P is paraposition and Ph is phenyl radical.

14 Example 3:

The results of molding of 10% short shot injection molding are summarized in Table 3.

TABLE 3

Blowing Decom- Kind of Molding Foaming Property of NO Agent posi- thermoTemp. Rate Molding foa- Addition tion plastic (0c) (Multiple) ming form Quantity Temp. resins formability ( OC) (shrink,warp) -Foaming,fine (a) Modified -surface,good 1 0.125. 282 PPE 290 1.092 -no shrink, no warp (b) Same as 2 0.200 285 PC 300 1.104 above (c) - Same as 3 0.125 276 PET 285 1.093 above 0.

(d) Saine as 4 0.200 276 PBT 280 1.098 above (e) 66 Same as 0.125 262 Nylon 275 1.089 above Wherein: (a) - (e) in Table 3 are same as in Table 2.

1 Example 4:

After mixing 5 weight % powder of the 1-pnitrophenol-5-ethyl-tetrazole to the copolymerized polyester powder (M.P. 140'C) and these mixtures are melt extruded and granulated, and the fixed amount of thesd granulated particles are mixed with the polyethylene tprephthalate resin chips having the limiting viscosity 0.72 (measured in the solution of tetrachloroethane/phenol = 2: 3 at 300C) and these are dried under reduced pressure and after regulating the water content of them under 50 ppm, the temperature of the resins is raised to 2800C and melted, extruded as a roll, and solidified on cooling and are manufactured the sheet having 5mm thick the properties of the obtained sheets are summarised in Table 4.

Comparative Experiment 1:

Poiyethylene terephthalate resins which are the same as used in the Example 4, are melted and manufactured the extruded sheets same as the conditions of Example 4 and the properties of sheet is recorded in the Table 4 together.

c - 16 TABLE 4

Blowing Agent Appearance Density Foaming Rate Addition (multiple) Quantity (5) Experi- 0.125 White Opaque 1.20 1.12 ment 4 0.25 Same as above 1.11 1.21 0.50 Same as above 1.02 1.32 Compara- tive Ex- ---- Semitrans- 1.35 ---- periment parent 1 Example 5:

Crystalline Cu salt of 5-methyl-1H-tetrazole (a) (decomposition temperature (2870C) which is finaly pulverized with the mortar are added the limitted weight shown by Table 5 to the PPS (polyphenylene sulphide) M.P. 2271C) and mixed them carefully so as to that (a) adheres equally to the chip surface of the PPS and they are melted and injection molded by the same condition shown by the Table 5, and the results are summerized in Table 5.

Table 5

Addition Ifi.jection Die Temp. Injection Foamine Rate Qty (%) Temp. ( C) ( OC) Condition (multiple) No. 1 1.002 2 1.025 0.125 3 1. 0 C5 4 1.075 1.125 320 140 No. 1 1.005 2 1.50 0.25 3 1.075 4 1.125 1.175 No. 1 1.025 2 1.060 0.50 3 1.100 4 1.175 1.125 1 Wherein: Injection condition No. No. 2: No. 3: No. 4: No. 5:

Example 6:

k full shot 3.7% short shot 7.4% short shot 11.1% short shot 14.5% short shot According to the Example 3, the foamed plastics are manufactured using various plastics and the results are summerized in Table 6.

TABLE 6

Blowing Decom- Kind of Molding Foaming Property of NO Agent posi- thermoTemp. Rate Molding,foa- Addition tion plastic (0c) (Multiple) ming form Quantity Temp. resins formability (OC) (shrink,warp) - Surface (a) beautiful 1 0.125 287 PPS 320 1.002 - no shrink, no warp (b) Same as 2 0.150 322 PEI 360 1.007 above (C) Same as 3 0.200 363 PES 370 1.013 above (d) - Surface 4 0.125 376 390 1.003 beadtiful - No shrink, no warp.

(e) Same as 0.150 399 PPEK 400 1.506 No. 1 18 Wherein: The blowing agents used in the Table 6 are as follows:

(a) N - N N - N ] 1 l H3C / \ N / (c) c N N C - CH3 H C, N N CU/ N N - N N - N JI 11.,. 11 11 (b) N - N N - N 11 11 N C H Zn (d) 1.."

N N - N N - N 11 1111 11 H3C[12C 'IC N N C - CH2CH3 c N N c N P r N N Zn (e) N - N N - N 11 11 11 1 HC N h ' H N N \-" C a/ Wherein: Pr is -CH2CH2C133 Zn 1 Example 7

Similar to the Example 3 and 4, blowing agents are added to the thermoplastic synthetic resins described in the Table 7 and molded to 10% short shot, and the results are summerized in Table 7.

TABLE 7

Blowing Decom- Kind of Molding Foaming Property of NO Agent posi- thermoTemp. -Rate Molding foa- Addition tion plastic coc) (multiple) ming form., Quantity Temp. resins formability COO (shrink,warp) - Foaming fine (f) - Surface 0.125 287 PPS 320 1.062 beautiful 1 - no shrink, no warp (g) Same as 2 0.1511, 322 PEI 360 1.118 above (h) Same as 0.200 363 PES 370 1.125 above W 4 0.125 376 390 1.073 Same as above (j) Same as 0.150 399 PPEK 400 1.119 No. 1 Wherein: The blowing agents (f) - (j) in the Table 7 are as follows (f) N - N N - N l 11 11 11 (9) N - N N - N il i 1 11 c N N C - CH3 N N CH H3C N Cu N N 11 Zn N (h) N - N N - N W 11., 11 N - N N1 - N 1111 11 H3C112C -C - N N C - C112C1i3 c N N c N N Pr N N Pr Zn (j) N - N N - N 11 11 11 11 N tic N N CH Ca N Wherein: Pr is --]2CH2CH3 Zn 21 -

Claims

1 The use as a blowing agent in the manufacture of a foamed thermoplastic synthetic resin of a tetrazole compound having a formula as follows N N 11 11 - N c N=C X R R2 C-N R N-M-N N=N N=N R (1) W N N A A N C-R2 N 1 m 1 z W) / R 1 \ N=C C=N N-M-N / 1 N=N N=N rnri j N=C-C=N - \ N-M-N / 1 1 i/ N=N N=N (M) where R and RI are the same or different and are selected from H, Cl to C6 alkyl, cycloalkyl or alkenyl radicals, optionally substituted by one or more Cl to C6 alkyl, -OH, -COOH, -S03H, -N02, halogen, and -NROS, wherein R4 and R5 may each be H or Cl - C4 alkyl, or R and Rl can be phenyl, benzyl or phenethyl radicals optionally substituted by 1 to 3 halogen, -OH, N02, -CN, -COOH, and -NR4R5. wherein R4 and R5 are as defined above; R2 is selected from H, -OH, -COOH, -S03H, -N02r halogen or -NR4R5r wherein R4 and R5 are as defined 22 - above, Cl to C6 alkyl, cycloalkyl or alkenyl, optionally substituted by Cl to C6 alkyl, OH, COOH, -S03H, -N02, halogen, -NR05. wherein R4 and R5 are as defined above or R2 can be phenyl, benzyl or phenethyl radicals optionally substituted by 1 to 3 halogen, -OH, -N02, -NR05. wherein R4 and R5 are as described above, Cl to C4 alkyl and esters or amides of lower carboxylic acids; R3 is selected from Cl to C6 alkylene, cycloalkylene, or alkenylene, optionally substituted by Cl to C6 alkyl, -6H, -COOH, S03H, -N02, halogen, or -NR4RS, wherein R4 and R5 are as defined above, the alkylene, cycloalkylene or alkenylene radicals optionally containing -0-, -S-Y -S02r CO-, phenylene and bisphenylene within the carbon chain, the phenylene and bisphenylene being optionally substituted by 1 to 8 halogen, -OH, N02, esters or amides of lower carboxylic acids, -NR05 wherein R4 and R5 are as defined above, and Cl to C4 alkyl; M is a divalent metal selected from Ca, Cu, Zn, Mn, Fe, Co, Ni and Ba; and Z is a univalent inorganic or organic radical which may bind to or form a salt with M.

2 The use of a blowing agent as claimed in claim 1, wherein Z is -S04r NH4r -HC03. -HP04r -N03, -ONH4r -CH31, -C2H5, -CHO, -NH2 or S03H.

3 A composition comprising at least one thermo plastic synthetic resin and from 0.01 to 15 weight % based on the weight of the thermoplastic synthetic resin of at least one tetrazole compound used in claim 1 or claim 2.

4 A method of producing a foamed polymeric material which method comprises premixing a first polymeric material with a blowing agent used in claim 1 or claim 2 to form a premix, forming the premix into chips or pellets, adding the chips or pellets to a second polymeric material to form a substantially homogeneous mixture and moulding the mixture.