CN101963610A - Method for representing curing degree of tire - Google Patents

Abstract

The invention provides a method for representing curing degree of a tire. When curing time t' is less than t90, the tire is in an under-cured state, when the curing time t' is more than tREV97, the tire is in an over-cured state, and otherwise, the tire is in an optimum cure state; and according to the criterion, S is called curing offset degree and indicates the degree of deviation of a sizing material curing state from the peak torque. The curing offset degree S is used for representing the curing degree, so that the curing state (optimum cure, under cure or over cure) of the sizing material at the part can be known, and the over-cured or under-cured degree of the sizing material can be clearly known. If the torque is used for expressing the comprehensive performance of the sizing material, the comprehensive performance of the sizing material is reduced by 7 percent compared with that of the sizing material in the optimum cure state when S is equal to 10, namely part of the sizing material is over-cured by 7 percent. In a similar way, when S is equal to -20, part of the sizing material is under-cured by 10 percent, so that the state of the sizing material can be accurately expressed.

Description

A kind of characterizing method of tyre vulcanization degree

Technical field

The present invention relates to a kind of characterizing method, be specifically related to the characterizing method of tyre vulcanization degree.

Background technology

Fig. 1 has provided the various performances of rubber curve over time.Along with the increase of cure time, the tensile elongation of rubber, stress at definite elongation and elasticity increase afterwards earlier and reduce; Hardness increases gradually and is tending towards certain value; Elongation takes the lead in reducing the back to be increased; Permanent strain reduces gradually and also is tending towards certain value.Therefore must take all factors into consideration sizing material various performance demands are determined cure time according to the purposes of rubber.In general, when sizing material was in the optimum cure state, its various performances all were in optimum condition, therefore should make each position sizing material all be in the optimum cure state in vulcanizing as far as possible.State of cure (vulcanization) is to be used for representing rubber in sulfidation, the comparison of main performance of sizing material (combination property) and optimum performance.At present state of cure (vulcanization) simply is divided into optimum cure on the engineering, owes sulphur and three kinds of states of over cure.Along with finite element technique is used to the simulation of curing temperature field, only qualitatively the rubber vulcanization state is estimated the optimization that can't finish the state of cure (vulcanization) field, therefore must be quantitatively described state of cure (vulcanization).

Optimum cure claims the most suitable sulfuration again, and the main performance (combination property) that is meant rubber reaches or near the sulfided state of optimum condition value.Owe sulphur and be meant the sulfided state that is in optimum cure early stage.Over cure is meant the sulfided state that is in the optimum cure later stage.The vulcanizating glue physical performance that is in the back two states is all relatively poor, industrially should avoid occurring this two states as far as possible.Sulfurizing time is meant that rubber reaches the required time of optimum cure state, and from curing curve (as shown in Figure 2) as can be seen, sulfurizing time is a scope, rather than a point.For the definition of over cure, each enterprise has nothing in common with each other.By the research to the various performance change trend of typical rubber material, most of performances are at t _REV97After can occur descending significantly, therefore can select t _REV97End point as the smooth phase.T wherein _REV97Drop to 97% o'clock pairing cure time of torque capacity for the torque of vulcameter mensuration.

Vulcameter is the test apparatus that is exclusively used in the testing rubber vulcanization characteristics that occurs in recent years.The principle that vulcameter is measured optimum cure is a shear modulus G ' be directly proportional with cross-linking density G, and the curve essence that the vulcameter registering instrument is drawn is exactly shear modulus G ' (torque) becomes forward with cure time torque change curve, as shown in Figure 2.Utilize vulcameter can directly determine initial cure time (time of scorch, induction period), theoretical sulfurizing time (t _H), technology sulfurizing time (t ₉₀), the counter-rotating 97 cure time (t _REV97) and cure rate index 100/ (t ₉₀-t _s).Present many units time of scorch adopts t ₁₀, that is torque reaches M _L+ 10% (M _H-M _L) pairing cure time, maximum sulfurizing time adopts counter-rotating 97 cure times, i.e. and torque drops to M from maximal value _L+ 97% (M _H-M _L) pairing cure time.Thereby can draw three kinds of states of cure (vulcanization) the interval of corresponding cure time.As cure time t '＜t ₉₀The time be undervulcanization state, as cure time t '＞t _REV97The time be the over cure state, otherwise for the optimum cure state.

Theoretical according to sulfuration, the performance of vulcanizate depends on G, that is cross-linking density.Therefore under different conditions of vulcanizations, make vulcanizate with identical mechanical property, just should make the cross-linking density G of various vulcanizates identical, normal equivalent vulcanization time (t ') and the equivalent cure effect of adopting characterizes G, and the merchant that the definition crosslinking degree equals equivalent vulcanization time and technology sulfurizing time characterizes G.Introduce existing three kinds of characterizing methods below in detail.

1) equivalent vulcanization time characterizing method

Equivalent vulcanization time is meant in the sulfidation that rubber is issued to the cure time of identical cure efficiency in different temperatures.In the sulfidation of tire, because the characteristic of the hot poor conductor of the geometrical non-linearity of tire and sizing material makes that the curing temperature at each position is time dependent.For the ease of weighing the state of cure (vulcanization) of sizing material under different temperatures, introduced equivalent vulcanization time.Therefore cure time and properties of rubber under the constant temperature sulfided state have one-to-one relationship, goods are converted into the equivalent vulcanization time under a certain standard temperature at the employing The Arrhenius Equation (Arrhenius equation) of the cure time under the different temperatures or Van't Hoff formula (Van ' t Hoff equation).

The expression-form of The Arrhenius Equation (Arrhenius equation):

$\ln \left(\frac{{\mathrm{\τ}}_1}{{\mathrm{\τ}}_2}\right)=\frac{E(T_2-T_1)}{{\mathrm{RT}}_2{T}_1}---\left(1\right)$

In the formula: τ ₁---temperature is T ₁The time sulfurizing time;

τ ₂---temperature is T ₂The time sulfurizing time;

R---gas law constant R=8.314J/ (molK);

E---vulcanization reaction energy of activation, J/mol.

Van't Hoff equation (Van ' t Hoff equation) curing temperature and time relation expression-form are as follows:

$\frac{{\mathrm{\τ}}_1}{{\mathrm{\τ}}_2}{=K}^{\frac{T_2-T_1}{10}}---\left(2\right)$

In the formula: τ ₁---temperature is T ₁The time sulfurizing time;

τ ₂---temperature is T ₂The time sulfurizing time;

K---temperature coefficient of vulcanization.

Temperature coefficient of vulcanization K is different because of the difference of sizing material, but general K gets 1.5～2.5, preferably gets 2.Like this in obtaining sizing material behind the each point temperatur-timel curve, can obtain the equivalent vulcanization time under a certain standard temperature by The Arrhenius Equation (Arrhenius equation) or Van't Hoff formula (Van ' t Hoff equation).Then to the technology sulfurizing time (t of the curing curve under should standard temperature ₉₀) and counter-rotating 97 cure time (t _REV97) can determine whether this sizing material is in the optimum cure interval.

2) equivalent cure effect characterizing method

By the calculating of equivalent cure effect, can make rubber under different conditions of vulcanizations, produce vulcanizate with same physical mechanical property.Sulfuration effect is represented state of cure (vulcanization), and the sulfuration effect value is big more, and the expression state of cure (vulcanization) is dark more.Sulfuration effect equals the product of sulfurating strength and time.

$E=\mathrm{It}=K^{\frac{T-100}{10}}t---\left(3\right)$

In the formula: E---sulfuration effect;

I---sulfurating strength;

T---cure time.

K---temperature coefficient of vulcanization;

T---curing temperature, ℃.

Sulfurating strength is meant sizing material under certain temperature, the state of cure (vulcanization) in the unit interval, and it has characterized the rate of cure of sizing material under this kind temperature.Sulfurating strength is relevant with curing temperature and temperature coefficient of vulcanization.Temperature coefficient of vulcanization is the temperature coefficient of vulcanization in the Van't Hoff formula herein.Therefore there is following relation in the equivalent cure effect with the equivalent vulcanization time that calculates with the Van't Hoff formula:

t′＝E/I _t (4)

In the formula: E-equivalent cure effect;

I _tSulfurating strength under the-a certain standard temperature;

T '-equivalent vulcanization time.

It is of equal value with adopting Van't Hoff formula calculating equivalent vulcanization time to characterize state of cure (vulcanization) that the equivalent cure effect is adopted in this explanation.Yet, in the temperature range that test allows, utilize the The Arrhenius Equation result calculated more accurate than the Van't Hoff formula for the not calculating of isothermal vulcanization.Therefore in the discussion of back, mainly introduce the equivalent vulcanization time that adopts The Arrhenius Equation to calculate.

3) crosslinking degree characterizing method

Utilize the equivalent vulcanization time of each position sizing material of Arrhenius Equation for Calculating tire, and definition crosslinking degree G is equivalent vulcanization time (t ') and technology sulfurizing time (t ₉₀) the merchant.That is crosslinking degree:

$G=\frac{t^{\′}}{t_{90}}---\left(5\right)$

When equivalent vulcanization time (t ') equals the cure time (t of sizing material when the smooth phase finishes ₉₀) time, use G _mRepresent the maximum state of cure (vulcanization) that this sizing material allows.When G less than 1 the time, sizing material is in the sulphur state of owing; When G greater than G _mThe time, sizing material is in the over cure state; When G 1 and G _mBetween the time, sizing material is in the optimum cure state.

Making a general survey of above-mentioned three kinds of methods that characterize state of cure (vulcanization), all is the linear function of state of cure (vulcanization) being regarded simply as equivalent vulcanization time.Yet from the curing curve of sizing material as can be seen, the performance of sizing material is highly non-linear with the variation of cure time, thereby the sulphur degree of owing and over cure degree that can not the accurate description sizing material.For example: adopting the sulfurizing time of certain sizing material under 151 ℃ is 1000 seconds, and 97 cure times that reverse are 1500 seconds, when equivalent vulcanization time is 900 seconds and 1800 seconds, asks it to owe sulphur degree and over cure degree respectively.Owe sulphur degree and over cure degree accurately if adopt above-mentioned three kinds of characterizing methods to obtain, and must find torque under the equivalent vulcanization time correspondence just can obtain it and owe sulphur and over cure degree by the inquiry curing curve.This brings a lot of troubles for undoubtedly the differentiation of state of cure (vulcanization).

Summary of the invention

The objective of the invention is to have the state that the qualitative description sulfuration is only arranged now in tyre industry, and lack the problem that a quantitative target characterizes the tyre vulcanization state, and then a kind of characterizing method of tyre vulcanization degree is provided in order to solve.

The characterizing method of tyre vulcanization degree of the present invention:

According to curing curve figure (shown in Figure 2) M ₁₀, M ₉₀Deng definite method of coefficient, similarly define M _n, wherein n is the positive number smaller or equal to 100.Thereby have

M _n＝M _L+(M _H-M _L)×n％ (1)

According to the vulcameter curve as can be known, M _nBe the function of t ', can be write as

M _n＝L(t′) (2)

Simultaneous formula (3) and formula (4) can get

n＝L’(t′) (3)

Therefore, n is the function of equivalent vulcanization time (t '), always has a n corresponding with it for a t '.Definition

$S=\left\{\begin{array}{cc}n-100& t_n<{\mathrm{<figure-callout\; id="100"\; label="t"\; filenames="HSA00000237091900101.png"\; state="\{\{state\}\}">t</figure-callout>}}_{100}\\ 100-n& {\mathrm{<figure-callout\; id="100"\; label="t"\; filenames="HSA00000237091900101.png"\; state="\{\{state\}\}">t</figure-callout>}}_{100}\&le;t_n\end{array}\right.---\left(4\right)$

According to working as cure time t '＜t ₉₀The time be undervulcanization state, as cure time t '＞t _REV97The time be the over cure state, otherwise, then have for the criterion of optimum cure state

S is called the sulfuration bias levels, and expression rubber vulcanization state departs from the degree of torque capacity.Bias levels S characterizes state of cure (vulcanization) with sulfuration, not only can know the sulfided state (sulfuric, owe sulphur or over cure) of this position sizing material, also can clearly know the sizing material over cure or to owe the sulphur degree.If represent the combination property of sizing material with torque, when S=10, represent that the relative optimum cure state of combination property of this sizing material has descended 7% so, this part sizing material over cure just has been described 7%.With should S=-20 the time, represent that this part sizing material owes sulphur 10%.

As can be seen from the above discussion, sulfuration bias levels S is a parameter based on properties of rubber, what its characterized is that the sizing material torque is in the position between torque capacity and the minimum torque, and to adopt sign to differentiate this torque be for the first half of curing curve or latter half of.So just can accurately give expression to the state of sizing material, with and over cure degree and owe the sulphur degree.

The present invention prove that the sulfuration bias levels can accurately characterize the performance state of sizing material, and other characterizing method can't be represented by several different characterizing methods of contrast.Thereby lay the foundation for the realization of state of cure (vulcanization) in finite element, also provide foundation more accurately simultaneously for formulating sulfuration process.

Description of drawings

Fig. 1 is the various performances of rubber curve maps over time,

Fig. 2 is curing curve figure,

Fig. 3～Fig. 7 is the distribution plan of the sulfuration bias levels S at each each position of tire constantly of temperature rise period,

Fig. 8～Figure 11 is the distribution plan of the sulfuration bias levels S at each each position of tire constantly of temperature-fall period,

Sulfuration bias levels distribution plan when Figure 12 is t=8400s,

Sulfuration bias levels distribution plan when Figure 13 is t=7680s,

Sulfuration bias levels distribution plan when Figure 14 is t=7080s,

Figure 15 is T _qSulfuration bias levels distribution plan in the time of=150 ℃,

Figure 16 is T _qSulfuration bias levels distribution plan in the time of=140 ℃,

Sulfuration bias levels distribution plan when Figure 17 is Tq=135 ℃,

Figure 18 is that the sulfuration bias levels distribution plan of glue is protected in the rim of the mouth before optimizing,

Figure 19 is that glue vulcanization characteristics curve map is protected in the rim of the mouth before and after optimizing,

Figure 20 is that the sulfuration bias levels distribution plan of glue is protected in the rim of the mouth after optimizing,

Figure 21 is a state of cure (vulcanization) field pattern of adjusting rear tyre.

1-pulling strengrth among Fig. 1; The 2-stress at definite elongation; 3-elasticity; The 4-length growth rate; 5-hardness; The 6-permanent strain.M among Fig. 2 _L-minimum torque; M _H-torque capacity; t _H-theoretical sulfurizing time; t ₁₀-time of scorch; t ₉₀-technology sulfurizing time; t _REV97-counter-rotating 97 cure times; M ₁₀=M _L+ (M _H-M _L) * 10%; M ₉₀=M _L+ (M _H-M _L) * 90%; M _REV97=M _L+ (M _H-M _L) * 97%.

Embodiment

The present invention proposes a kind of new state of cure (vulcanization) characterizing method by existing state of cure (vulcanization) characterizing method is studied, and this characterizing method is applied in the middle of the example of calculation shows.By contrasting several different characterizing methods, find that this new state of cure (vulcanization) characterizing method can accurately characterize the performance state of sizing material, thereby lay the foundation for the realization of state of cure (vulcanization) in finite element, also provide foundation more accurately simultaneously for formulating sulfuration process.

For this reason, provide a kind of new characterizing method---the sulfuration bias levels.

The definition of sulfuration bias levels:

In engineering was used, what be concerned about most was the mechanical and physical performance and the chemical property of sizing material, so state of cure (vulcanization) also should be able to embody these performances of sizing material intuitively.According to shown in Figure 2, according to M ₁₀, M ₉₀Deng definite method of coefficient, similarly define M _n, wherein n is the positive number smaller or equal to 100.Thereby have

M _n＝M _L+(M _H-M _L)×n％ (1)

According to the vulcameter curve as can be known, M _nBe the function of t ', can be write as

M _n＝L(t′) (2)

Simultaneous formula (3) and formula (4) can get

n＝L’(t′) (3)

Therefore, n is the function of equivalent vulcanization time (t '), always has a n corresponding with it for a t '.

Definition

$S=\left\{\begin{array}{cc}n-100& t_n<{\mathrm{<figure-callout\; id="100"\; label="t"\; filenames="HSA00000237091900101.png"\; state="\{\{state\}\}">t</figure-callout>}}_{100}\\ 100-\mathrm{<figure-callout\; id="100"\; label="n\; t"\; filenames="HSA00000237091900101.png"\; state="\{\{state\}\}">n</figure-callout>}& t_{}{}_{100}\&le;t_n\end{array}\right.---\left(4\right)$

According to working as cure time t '＜t ₉₀The time be undervulcanization state, as cure time t '＞t _REV97The time be the over cure state, otherwise, then have for the criterion of optimum cure state

S is called the sulfuration bias levels, and expression rubber vulcanization state departs from the degree of torque capacity.Bias levels S characterizes state of cure (vulcanization) with sulfuration, not only can know the sulfided state (sulfuric, owe sulphur or over cure) of this position sizing material, also can clearly know the sizing material over cure or to owe the sulphur degree.If represent the combination property of sizing material with torque, when S=10, represent that the relative optimum cure state of combination property of this sizing material has descended 7% so, this part sizing material over cure just has been described 7%.With should S=-20 the time, represent that this part sizing material owes sulphur 10%.

As can be seen from the above discussion, sulfuration bias levels S is a parameter based on properties of rubber, what its characterized is that the sizing material torque is in the position between torque capacity and the minimum torque, and to adopt sign to differentiate this torque be for the first half of curing curve or latter half of.So just can accurately give expression to the state of sizing material, with and over cure degree and owe the sulphur degree.

The application and the advantage of sulfuration bias levels:

Adopted aforesaid equivalent vulcanization time, crosslinking degree and three kinds of modes of sulfuration bias levels to express the state of cure (vulcanization) field.Fig. 3～Fig. 7 has provided the distribution plan of the sulfuration bias levels S at each each position of tire constantly of temperature rise period, and Fig. 7～Figure 10 has provided the distribution plan of the sulfuration bias levels S at each each position of tire constantly of temperature-fall period.

At 9780 seconds constantly, the tire shoulder centre has just begun to take place vulcanization reaction, and at temperature-fall period, its sulfuration bias levels S increases rapidly.On the whole, the surfaces externally and internally of tire all is in the over cure state, and full tire does not have undervulcanization position, and the maximal value of sulfuration bias levels S is 22.93, and this has illustrated in this part sizing material maximum over cure 19.93%.Minimum value is-1.706, and this illustrates that this sulfuration process is unreasonable, not only reduces the quality of tire but also wasted a large amount of energy.

Therefore, adjust the state of cure (vulcanization) of whole tire by shortening cure time.Figure 11～Figure 14 is the sulfuration bias levels distribution plan under the different cure times.As can be seen from the figure, through repeatedly adjusting cure time, when cure time t=7680s, the state of cure (vulcanization) at each position of tire distributes comparatively desirable, has only surfacing to be in the over cure state, does not have the position sulphur phenomenon to occur owing.This compares with optimizing preceding cure time, has saved 2100 second time.

Keeping under the constant prerequisite of cure time, can be by improving or reduce the sulfided state that curing temperature is adjusted each position.The curing temperature of adjusting a certain position has considerable influence to the state of cure (vulcanization) of adjacent material, and less to sulfided state sulfuration at a distance.

After cure time was optimized, each position of tire mostly was in the optimum cure state, but tire tread face and inside surface are in serious over cure state, shown in Figure 15 figure.The serious over cure on decorative pattern surface can cause the decorative pattern breach, take off mass defect such as piece, and the curing temperature that therefore must prolong the smooth phase of sulfuration of tread rubber or reduce this position makes them be in the optimum cure state.Present embodiment will adopt the method for the curing temperature that reduces this position to be optimized.

The segmented mold temperature at decorative pattern place is reduced to 140 ℃, and cure time adopts the cure time 7680 seconds after the above-mentioned optimization, vulcanizes simulation calculation.As can be seen from Figure 16, the over cure degree of tyre tread has obtained certain improvement, and the change of the state of cure (vulcanization) of the sizing material at other position of tire is very little, and the just interior sulfuration bias levels of line with rubber at the tire shoulder place drops to-10.85, is in slight undervulcanization state.Therefore continue to attempt to cross the segmented mold temperature and reduce to 135 ℃, calculate the state of cure (vulcanization) field once more.As can be seen from Figure 17, the over cure degree of surface of tyre has obtained very big improvement, and it is less to owe the influence of sulphur degree to shoulder, and the minimum value of sulfuration bias levels reduces to-11.77.Therefore can adjust the sulfided state of sizing material effectively by adjusting curing temperature.

In sum, the adjustment of cure time is the adjusting to the whole state of cure (vulcanization) of tire field, and the adjustment that is to say cure time all has considerable influence to the state of cure (vulcanization) at each position of tire.And the curing temperature at a certain position is adjusted, then only change the state of cure (vulcanization) of adjacent regions material.Therefore in the optimizing process of sulfuration process, when most of position of whole tire is in unfavorable sulfided state, by regulating the sulfided state that cure time can change each position of tire effectively.When only needing to adjust the state of cure (vulcanization) at a certain position, then can realize by adjusting curing temperature.

Through after calculating several times, under the prerequisite that does not change cure time, the segmented mold temperature is adjusted into 135 ℃, other process conditions all do not change, and can obtain state of cure (vulcanization) field distribution preferably.Therefore at last the segmented mold temperature is decided to be 135 ℃.The reduction of segmented mold temperature also can be saved a large amount of energy, reduces the production cost of tire.

After to sulfuration process optimization, though the tire major part all is in the optimum cure state, yet also be in more serious over cure state, and the tire shoulder position of interior line with rubber exists also slight undervulcanization at tire inner surface.Continue adjusting sulfuration process makes these places be in the optimum cure state and the sulfided state that do not influence other positions is difficult to accomplish.Therefore, can only be optimized, just can make these positions reach optimum cure, and not influence the sulfided state at other positions from the performance of material.Protecting glue with the rim of the mouth is example, and before optimization, the surface that glue is protected in the rim of the mouth mostly is in serious over cure state, shown in canescence among Figure 18.After adjusting the rim of the mouth and protecting the curingprocess rate of glue, acquisition rim of the mouth as shown in figure 20 protect glue curingprocess rate distribution plan.As can be seen from the figure, after the adjustment, most of rim of the mouth is protected glue and all is in the optimum cure state.

After the above-mentioned optimization of process, the state of cure (vulcanization) field distribution of whole tire has obtained very big improvement.Figure 21 is for optimizing after cure bias levels distribution plan.Itself and Figure 11 are compared, be not difficult to find out, adopt the sulfuration bias levels can accurately reflect the sulfided state of sizing material, thereby be that formulation and optimization sulfuration process are provided convenience.After the optimization, cure time has shortened 35 minutes, the segmented mold temperature of tyre tread portion is reduced to 135 ℃, most of sizing material all is in the optimum cure state, have only some positions of surfaces externally and internally to have over cure, saved the energy greatly, improved the overall performance of tire, also improved production efficiency simultaneously, for enterprise creates more economic benefit.

By contrasting several different characterizing methods, find that the sulfuration bias levels can accurately characterize the performance state of sizing material, and other characterizing method can't be represented.Thereby lay the foundation for the realization of state of cure (vulcanization) in finite element, also provide foundation more accurately simultaneously for formulating sulfuration process.

The above; only for the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (1)

1. the characterizing method of a tyre vulcanization degree is characterized in that:

According to M among the curing curve figure ₁₀, M ₉₀Definite method of coefficient, definition M _n, wherein n is the positive number smaller or equal to 100; Thereby have

M _n＝M _L+(M _H-M _L)×n％ (1)

According to the vulcameter curve as can be known, M _nBe the function of t ', write as

M _n＝L(t′) (2)

Simultaneous formula (3) and formula (4) can get

n＝L’(t′) (3)

Therefore, n is the function of equivalent vulcanization time (t '), always has a n corresponding with it for a t '; Definition

$S=\left\{\begin{array}{cc}n-100& t_n<t_{100}\\ 100-n& t_{100}\&le;t_n\end{array}\right.---\left(4\right)$

According to working as cure time t '＜t ₉₀The time be undervulcanization state, as cure time t '＞t _REV97The time be the over cure state, otherwise, then have for the criterion of optimum cure state

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