CN115414271B

CN115414271B - Shower gel with good skin feel after use

Info

Publication number: CN115414271B
Application number: CN202210950502.5A
Authority: CN
Inventors: 刘�英; 梁勇伟; 何一波; 王伟; 蒋唯峰; 翁士威; 张蕾
Original assignee: Nice Zhejiang Technology Co ltd; Nice Group Co Ltd
Current assignee: Nice Zhejiang Technology Co ltd; Nice Group Co Ltd
Priority date: 2022-08-09
Filing date: 2022-08-09
Publication date: 2023-09-15
Anticipated expiration: 2042-08-09
Also published as: CN115414271A

Abstract

The invention relates to the technical field of bath cream, and discloses a bath cream with good skin feel after use. The bath lotion comprises the following components: cocoamides, sodium lactate and glycerol polyether; the cocoamide substance is cocoamide MEA and/or cocoamide methyl MEA. According to the invention, three components of cocoamide substances, sodium lactate and glycerolyether are compounded, a synergistic effect can be generated among the three components, a hydration film is formed on the surface of skin, and double protection is formed, so that the skin feel of the shower gel after use is improved to a greater extent.

Description

Shower gel with good skin feel after use

Technical Field

The invention relates to the technical field of body washes, in particular to a body wash with good skin feel after use.

Background

The shower gel is a main development direction of domestic shower agents in recent decades because of the advantages of convenient use, simple process and the like, and the sales volume is dominant in the market. Along with the rapid improvement of the living standard of people, the requirements of consumers on the quality of products are higher and higher, the basic cleaning function of the products is not limited, the mildness of the products is also prioritized when the bath lotion is purchased, and the products with skin care components or effects are more popular. The body wash on the market at present generally focuses on the cleaning power and fragrance performance of products, and the research on improving the skin feel of the products after use is not more in the industry. The bath lotion has good skin feel after use, and is a technical problem in the industry all the time. Therefore, the development of the bath lotion which can reduce the irritation, moisturize and smooth the skin and has good skin feel after use has important significance.

At present, most of researches for improving skin feel after the bath lotion is used are focused on changing the types or compatibility of surfactants. For example, patent CN202111275798.7 discloses a high-foam body wash and a preparation method thereof, and by adding dodecyl dimethyl amine oxide and cocoyl amphoteric disodium diacetate, which are both zwitterionic surfactants, the use of anionic surfactants can be reduced, so that skin irritation is reduced; secondly, the stability of the bath foam can be enhanced by the compatibility of the two, and the skin cleaning effect is good; in addition, the compatibility of the two can increase the foam quantity generated during friction, and the foaming performance is excellent, and the foam is rich, so that the comfort of use is improved. However, the effect of improving the skin feel of the body wash is limited by optimizing the type or compatibility of the surfactant, and the research on the surfactant reaches the bottleneck period, so that the breakthrough is difficult.

Disclosure of Invention

In order to solve the technical problem that the skin feel of the shower gel is difficult to further improve in the prior art, the invention provides the shower gel with good skin feel after use. The bath foam is compounded with three components of cocamide substances, sodium lactate and glycereth, and the three components can mutually promote each other to generate a synergistic effect, so that the skin feel of the bath foam after use is improved to a greater extent.

The specific technical scheme of the invention is as follows:

a body wash with good skin feel after use, the body wash comprising the following components: cocoamides, sodium lactate and glycerol polyether; the cocoamide substance is cocoamide MEA and/or cocoamide methyl MEA.

Maintaining the proper water content in the stratum corneum is important for its function. If the stratum corneum outer layer does not have sufficient moisture to hold normal flexibility, the skin will become scaly and itchy, with reduced skin penetration. If the skin outer layer is too watery, it will cause the stratum corneum to absorb 3-5 times its own weight of bound water, causing the skin to bulge and pucker, while the skin permeability increases. Thus, helping the stratum corneum maintain its barrier and water retention functions is important for improving skin feel after use of the body wash.

Sodium lactate is a component which occupies one quarter of the human skin cuticle, and when the sodium lactate is added into the bath foam, the irritation of the bath foam can be reduced, and a certain moisturizing effect is brought; the glycerolyether is used as a humectant, and can improve the soft and lubrication texture of skin; after the cocoamidomea or cocoamidomethyl MEA remains on the skin, the cocoamidomethyl MEA or cocoamidomethyl MEA has a certain fat-imparting effect and can also have a moisturizing effect.

However, the team of the invention discovers that in the bath lotion, when sodium lactate, glycerol polyether or cocoamide substances are singly used, the effect of improving skin feel is limited, and when the three substances are compounded, the three substances can mutually promote to generate a synergistic effect, so that the skin feel after the use of the bath lotion is improved to a greater extent, and the supposition mechanism is as follows: the glycerol polyether, sodium lactate and water molecules can form a cross-linking hydrogen bond, so that a hydration film is formed on the surface of the skin to prevent the moisture from volatilizing, the moisturizing effect is better exerted, and the smooth feeling is brought; the cocoamide substances remain on the skin, have a certain lipid-forming effect, are matched with a hydration film, and can form double protection on the skin surface, so that the effect is further improved.

The synergistic effect equivalent to that of the glycerolyether can be realized without compounding any humectant with cocoamide substances and sodium lactate, because: firstly, a cross-linking hydrogen bond is formed to form a grid-like structure, so that the water-locking effect is better, and moisture preservation is realized; the skin surface is secondarily formed with a film layer structure, so that the integral water locking and moisturizing can be realized, and the skin surface can be comprehensively and uniformly covered based on the unique branched long polyether chain structure of the glycerol polyether, and the smooth feeling is brought while the moisture is preserved. Conventional other humectants, such as sodium pyrrolidone carboxylate, sodium hyaluronate, etc., do not form a similar structure and therefore do not have an equivalent synergistic effect.

Preferably, the bath lotion comprises the following components in percentage by mass: 1-10% of potassium cocoate, 3-13% of sodium lauryl ether sulfate, 1-5% of cocamidopropyl betaine and 1-5% of cocoyl glucoside.

Further, the bath lotion comprises the following components in percentage by mass: 0.1 to 2 percent of acrylic polymer, 0.1 to 2 percent of sodium chloride, 0.05 to 0.3 percent of disodium ethylenediamine tetraacetate, 0.1 to 0.5 percent of citric acid, 0.01 to 0.1 percent of kathon and 0.1 to 0.5 percent of phenoxyethanol.

Further, the bath lotion comprises the following components in percentage by mass: 0.5 to 1.5 percent of essence and 0.0001 to 0.01 percent of pigment.

Preferably, the bath lotion further comprises the following components: alkyl glycoside sulfosuccinate salt.

The irritation of body washes is a key factor that causes skin changes and affects the use experience. Anionic surfactants such as sodium fatty alcohol sulfate commonly used in body washes can penetrate the stratum corneum membrane and provide degreasing action to damage the integrity of the stratum corneum membrane, and damage to the skin surface structure can cause rough feel and even pain feel. Thus, the irritation is reduced, and adverse effects on the skin can be significantly reduced.

After theoretical analysis and experimental research, the team of the invention finds that the alkyl glycoside sulfosuccinate salt can be used for reducing the irritation of the bath cream, and the mechanism is as follows: the alkyl glycoside sulfosuccinate salt contains a plurality of strong hydrophilic groups, has strong hydrophilicity, is easier to be washed away in water when being used for bathing, and is not easy to be on the skin. And because of the characteristics of the structure, the skin care gel has the characteristics of non-ions and anions, and has good affinity with the commonly used anionic surfactant and non-ionic surfactant in the bath foam according to the similar principle, so that the commonly used anionic surfactant and non-ionic surfactant in the bath foam can be more easily washed away by water, the amount of the residual surfactant on the skin is reduced, and the irritation is greatly reduced.

In addition, after the sodium lactate, the glycerol polyether and the alkyl glycoside sulfosuccinate are compounded, a synergistic effect can be generated, so that the irritation of the shower gel is obviously reduced, and the skin feel of the shower gel after being used is improved. The mechanism of speculation is as follows: when the alkyl glycoside sulfosuccinate salt is not added, the components commonly used in the shower gel, such as a surfactant and an auxiliary agent, can be more remained on the skin, so that the formation of a crosslinked hydrogen bond structure and a hydration film layer structure among the glycerolyether, sodium lactate and water molecules is destroyed, and the formation of the crosslinked hydrogen bond and the hydration film can effectively prevent the volatilization of water, better play the moisturizing effect and bring a smooth feel, thereby improving the skin feel after the shower gel is used.

Preferably, in the shower gel, the total mass percentage of cocoamide substances, sodium lactate, glycereth and alkyl glycoside sulfosuccinate is 0.4-8%.

Preferably, the glycerol polyether comprises one or more of glycerol polyether-12, glycerol polyether-18 and glycerol polyether-26.

When the three glycerol polyethers are selected, the irritation of the bath foam can be reduced to a greater extent, and the skin feel of the bath foam after use is improved, because: the chain length of the polyether of the three glycerol polyethers is moderate, and the three glycerol polyethers can better form a crosslinking hydrogen bond with sodium lactate and water to form a hydration film; if the polyether chain length is too short, the crosslinked hydrogen bond network structure may be incomplete, and if too long, the hydrophilicity may be too strong, and the residual amount on the skin may be insufficient.

Preferably, the mass ratio of the cocoamide material, sodium lactate and glycerin polyether is (0.3-3): (0.1-1): (0.1-1).

In the cocoamide substances, sodium lactate and glycerin polyether, when the relative dosage of the cocoamide substances is too small, the body wash has insufficient fat-forming effect, poor moisturizing effect and influences skin feel after use; when the relative amount of sodium lactate is too small, the irritation reducing effect is reduced, and the moisturizing effect is reduced, presumably because the moisturizing effect of sodium lactate is superior to that of the glycerol polyether and cocoamide substances; when the amount of the glycerol polyether is too small, it is difficult to form a complete hydrated film, thereby causing a deterioration in moisturizing effect and smoothness.

Preferably, in the bath foam, the total mass percentage of sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate is 0.1-5%.

Within a certain range, the irritation of the bath lotion is reduced and the skin feel after use is improved along with the increase of the contents of the three components of the bath lotion; however, when the content reaches a certain value, the adsorption amount of the three components on the skin reaches saturation, the effect reaches a plateau peak value, the content of the three components is continuously increased, and the irritation of the bath lotion is difficult to be further reduced and the skin feel after the bath lotion is used is improved.

Preferably, the ratio of the total mass of the glycerol polyether and sodium lactate to the mass of the alkyl glycoside sulfosuccinate salt is (0.2-3): (0.3-3).

Based on the synergistic action mechanism between the glycerolyether and sodium lactate and the alkyl glycoside sulfosuccinate, the invention discovers that when the ratio of the total mass of the glycerolyether and sodium lactate to the mass of the alkyl glycoside sulfosuccinate is too large or too small, the effects of reducing the irritation of the shower gel and improving the skin feel after the shower gel is used are poor, and specifically: when the relative amount of the glyceryl polyether and the sodium lactate is too small, although the irritation is still obviously reduced, the moisturizing effect and smoothness are obviously reduced, on one hand, because the insufficient amount of the glyceryl polyether and the sodium lactate has better effect, and on the other hand, the excessive alkyl glycoside sulfosuccinate salt can also elute part of the glyceryl polyether and the sodium lactate, so that the residual amount of the glyceryl polyether and the sodium lactate on the skin is less, and the effect is less ideal; when the relative amount of the alkyl glycoside sulfosuccinate salt is too small, the decrease in the irritation is not remarkable, presumably because it is insufficient to drastically reduce the usual components of the body wash remaining on the skin, the irritation caused by the surfactant still exists, and at the same time, the relative amount of the glyceryl polyether and sodium lactate adsorbed on the skin is decreased, and the moisturizing effect and the smoothing effect are also not remarkable.

Preferably, the alkyl glycoside sulfosuccinate salt has the following general formula:

wherein R is C _8～16 N is 1.0 to 1.4.

Further, in the alkyl glycoside sulfosuccinate salt, R is C _12～16 Is a hydrocarbon group.

In alkyl glycoside sulfosuccinate salt, the alkyl glycoside sulfosuccinate salt is influenced by strong hydrophilic groups, and other surfactants in the bath foam can be better affinitized only by properly balancing the oleophilic capability of the alkyl glycoside sulfosuccinate salt, so that a better elution effect is realized, and the irritation of the bath foam is reduced, so that when an alkyl chain is in C _8～16 Better results are obtained when C is used as the alkyl chain _12～16 When the bath foam is used, the effect of reducing the irritation of the bath foam can be further improved.

When the polymerization degree (n) of the glycoside is between 1.0 and 1.4, the distribution range is narrow, and the influence is relatively small.

Compared with the prior art, the invention has the following advantages:

(1) According to the invention, three components of cocoamide substances, sodium lactate and glycerolyether are compounded, a synergistic effect can be generated among the three components, a hydration film is formed on the surface of skin, and double protection is formed, so that the skin feel of the shower gel after use is improved to a greater extent;

(2) According to the invention, the alkyl glycoside sulfosuccinate is added into the shower gel, so that the residue of the surfactant on the skin surface can be reduced, a synergistic effect can be generated with sodium lactate and glycereth, the irritation of the shower gel is better reduced, and the skin feel of the shower gel after use is improved;

(3) The invention can generate better synergistic effect by controlling the proportion of each component, effectively reduce the irritation of the bath cream and improve the skin feel after the bath cream is used.

Detailed Description

The invention is further described below with reference to examples.

General examples

A body wash with good skin feel after use, the body wash comprising the following components: cocoamides, sodium lactate, glycerol polyether, alkyl glycoside sulfosuccinate; the cocoamide substance is cocoamide MEA and/or cocoamide methyl MEA. In the shower gel, the total mass percent of cocoamide substances, sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate is 0.4-8%, and the total mass percent of sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate is 0.1-5%. The mass ratio of the cocoamide substance to the sodium lactate to the glycerol polyether is (0.3-3): (0.1-1): (0.1-1). The ratio of the total mass of the glycerol polyether and sodium lactate to the mass of the alkyl glycoside sulfosuccinate salt is (0.2-3): (0.3-3).

The bath foam comprises the following components in percentage by mass: 1 to 10 percent of potassium cocoate, 3 to 13 percent of sodium lauryl ether sulfate, 1 to 5 percent of cocamidopropyl betaine, 1 to 5 percent of coco glucoside, 0.1 to 2 percent of acrylic polymer, 0.1 to 2 percent of sodium chloride, 0.05 to 0.3 percent of disodium ethylenediamine tetraacetate, 0.1 to 0.5 percent of citric acid, 0.01 to 0.1 percent of kathon, 0.1 to 0.5 percent of phenoxyethanol, 0.5 to 1.5 percent of essence and 0.0001 to 0.01 percent of pigment.

In the bath foam, the total mass percentage of cocoamide substances, sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate is 0.4-8%.

The general formula of the alkyl glycoside sulfosuccinate salt is as follows:

wherein R is C _8～16 Alkyl (further preferably C) _12～16 Alkyl) and n is 1.0 to 1.4.

Examples 1 to 10 and comparative examples 1 to 5

The body wash formulations of examples 1-10 and comparative examples 1-5 are shown in Table 1.

In table 1, "-" indicates that the addition amount is 0; APG-SS1, APG-SS2 and APG-SS3 represent 3 different alkyl glycoside sulfosuccinate salts, and the structural general formulas are as follows:

the 3 alkyl glycoside sulfosuccinate salts differ as follows:

APG-SS1: sodium alkyl glycoside sulfosuccinate, R is C _8～10 Alkyl, n is 1.0;

APG-SS2: sodium alkyl glycoside sulfosuccinate, R is C _12～14 Alkyl, n is 1.2;

APG-SS3: sodium alkyl glycoside sulfosuccinate, R is C _12～16 Alkyl, n is 1.4.

TABLE 1

TABLE 2

TABLE 3 Table 3

Test example 1: irritation test

The samples to be tested (body washes of examples 1 to 10 and comparative examples 1 to 5) were formulated as 10wt% solutions. 50mL of zein was taken, 2g of zein was added, stirred at 25℃for 2h, observed every 10min, and zein was optionally added to ensure sufficient undissolved zein in the solution. Then standing and filtering, and measuring the mass fraction (A) of nitrogen in the filtrate by a micro Kjeldahl nitrogen determination method. And taking 50mL of the body wash without adding zein for blank experiments, and measuring the mass fraction (B) of nitrogen in the body wash solution without adding zein.

Zein value = a-B, zein value is expressed as mg (or g) of nitrogen contained in the solution, N mg (g)/L.

By Zein values, the irritation properties of surfactants can be classified into 3 classes:

(1) The surfactant with Zein value greater than N4 g/L solution is 'strong irritation'.

(2) The surfactant with Zein value of N2-4 g/L solution is 'low-irritation'.

(3) The surfactant with Zein value less than N2 g/L solution is 'non-irritating'.

The test results are shown in Table 4.

TABLE 4 Table 4

Shower gel	Zein value, N g/L
		Example 1	1.25
Example 2	6.52
		Example 3	2.81
Example 4	2.95
		Example 5	1.31
Example 6	2.27
		Example 7	1.72
Example 8	3.5
		Example 9	1.98
Example 10	2.67
		Comparative example 1	3.10
Comparative example 2	4.80
		Comparative example 3	5.11
Comparative example 4	2.92
		Comparative example 5	4.41

Test example 2: moisturizing effect

According to the cosmetic moisturizing efficacy evaluation guideline, at least 30 healthy volunteers are selected, the testing instrument is a Corneometer CM825, the testing place ensures constant temperature and humidity, the temperature is 20-22 ℃, and the relative humidity is 40-60%. The test subject needs to wash the inner sides of the forearms of the two hands, and after cleaning, marking the measurement areas on the inner sides of the forearms of the two hands of the test subject, wherein the area of each test area is 3cm multiplied by 3cm. Constant temperature and humidity room before testStill sitting in the room for at least 30min, can not drink water, exposes the forearm, avoids touching, and keeps relaxing. The moisture content (MMV value) of the designated region inside the left and right arms of the subject was measured and recorded. Initial values of each test area were measured, and then 1wt% aqueous solutions of samples (body washes of examples 1 to 10 and comparative examples 1 to 5) were uniformly applied to the test areas with latex finger cots, the single application amount was 0.2g/cm ² After 20 minutes of action, the test area was rinsed with clean water for 30 seconds and the surface was blotted with paper towels to remove residual moisture. MMV values were measured in the smeared area (test group) and in the blank area (blank group) 2 hours before and after the sample use, respectively. Testing of the same volunteer was done by the same measurer. The experimental results are shown in table 5.

TABLE 5

¹ Blank group: the bath cream is not smeared.

Test example 3: skin smoothness test after use

The use feeling of the product was evaluated by 30 subjects, and the evaluation parameters were: skin smoothness. The scores were rated according to a score of 1 to 4, with higher scores representing smoother skin. The results of statistics on the index scores of the subjects after using the products of examples 1 to 10 and comparative examples 1 to 5 are shown in Table 6.

TABLE 6

Data analysis and conclusion:

(1) In example 1, comparative example 1 and comparative example 2, the total content of cocamide, sodium lactate and glycerin polyether was the same, and in comparative example 1, no cocamide was added, and in comparative example 2, sodium lactate and glycerin polyether were not added. As can be seen from tables 4 to 6: the moisturizing effect and skin smoothness after use of example 1 are significantly higher than those of comparative examples 1 and 2. Conclusion: the synergistic effect of 1+1> 2' can be generated between the cocoamide substances, sodium lactate and glycerin polyether, and the skin feel of the shower gel after use can be improved to a greater extent after the three substances are compounded.

(2) In example 1, comparative example 3 and comparative example 4, the total content of sodium lactate and glycerolyether was the same, no glycerolyether was added in comparative example 3, and no sodium lactate was added in comparative example 4. As can be seen from tables 4 to 6: example 1 was less irritating than comparative examples 3 and 4, and the moisturizing effect and skin smoothness after use were significantly higher than comparative examples 3 and 4. Conclusion: the sodium lactate and the glycerol polyether can exert the synergistic effect of 1+1>2, and after the sodium lactate and the glycerol polyether are compounded, the irritation of the bath foam can be reduced to a greater extent, and the skin feel of the bath foam after use can be improved.

(3) The total content of alkyl glycoside sulfosuccinate salt, sodium lactate and glycerin polyether was the same in example 1, example 2 and comparative example 5, and no alkyl glycoside sulfosuccinate salt was added in example 2, and no sodium lactate and glycerin polyether were added in comparative example 5. As can be seen from tables 4 to 6: example 1 was significantly less irritating than example 2 and comparative example 5, and the moisturizing effect and skin smoothness after use were significantly higher than example 2 and comparative example 5. Conclusion: the alkyl glycoside sulfosuccinate salt can exert the synergistic effect of '1+1 > 2' with sodium lactate and glycerol polyether, and after the three are compounded, the irritation of the shower gel can be reduced to a greater extent, and the skin feel of the shower gel after being used is improved.

(4) Examples 3 and 5 employed glycerolyether-8 and glycerolyether-12, respectively, with the remainder being the same; example 4 and example 7 used glycerolyether-31 and glycerolyether-26, respectively, with the remainder being the same. As can be seen from tables 4 to 6: example 5 is significantly less irritating than example 3 and has significantly higher moisturization and skin smoothness after use than example 3; example 7 is significantly less irritating than example 4 and has significantly higher moisturization and skin smoothness after use than example 4. Conclusion: too long or too short polyether chain in the glycerolyether can cause bad effects of reducing the irritation of the bath cream and improving the skin feel after the bath cream is used.

(5) In examples 5 and 6, the total content of cocoamide, sodium lactate and glycerol polyether was the same, and the mass ratio of the three was 0.3:1:1 and 0.1:1.1:1.1, respectively; in examples 7 and 8, the total content of cocoamide, sodium lactate and glycerol polyether was the same, and the mass ratio of the three was 3:0.1:1 and 3.03:0.06:1.01, respectively; in examples 9 and 10, the total content of cocoamide, sodium lactate and glycerol polyether was the same, and the mass ratio of the three was 3:1:0.1 and 3.03:1.01:0.06, respectively. As can be seen from tables 4 to 6: example 5 shows a significantly higher moisturizing effect and skin smoothness after use than example 6; example 7 has a significantly higher moisturizing effect and skin smoothness after use than example 8; example 9 shows significantly higher moisturization and skin smoothness after use than example 10. Conclusion: any one of cocoamide substances, sodium lactate and glycerin polyether with too small relative content can have adverse effect on skin feel after the shower gel is used.

The raw materials and equipment used in the invention are common raw materials and equipment in the field unless specified otherwise; the methods used in the present invention are conventional in the art unless otherwise specified.

The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent transformation of the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. The shower gel with good skin feel after use is characterized by comprising the following components: cocoamides, sodium lactate, glycerol polyether, alkyl glycoside sulfosuccinate; the cocoamide substance is cocoamide MEA and/or cocoamide methyl MEA; the glycerin polyether comprises one or more of glycerin polyether-12, glycerin polyether-18 and glycerin polyether-26; the mass ratio of the cocoamide substance to the sodium lactate to the glycerol polyether is (0.3-3): (0.1 to 1): (0.1-1).

2. The body wash of claim 1, further comprising, in mass percent: 1-10% of potassium cocoate, 3-13% of sodium lauryl ether sulfate, 1-5% of cocamidopropyl betaine and 1-5% of cocoyl glucoside.

3. The body wash according to claim 2, further comprising the following components in mass percent: 0.1-2% of acrylic polymer, 0.1-2% of sodium chloride, 0.05-0.3% of disodium ethylenediamine tetraacetate, 0.1-0.5% of citric acid, 0.01-0.1% of pinus koraiensis and 0.1-0.5% of phenoxyethanol.

4. The body wash according to claim 2 or 3, further comprising the following components in mass percent: 0.5-1.5% of essence and 0.0001-0.01% of pigment.

5. The body wash according to claim 1, wherein the total mass percentage of cocoamide substances, sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate is 0.4-8%.

6. The body wash according to claim 1, wherein the total mass percentage of sodium lactate, glycerol polyether and alkyl glycoside sulfosuccinate salt in the body wash is 0.1-5%.

7. The body wash according to claim 1 or 6, wherein the ratio of the total mass of the glyceryl polyether and sodium lactate to the mass of the alkyl glycoside sulfosuccinate salt is (0.2-3): (0.3 to 3).